Insights on Diagnosing and Managing Cushing’s Syndrome

Posted on August 18, 2024 by MaryO

Cushing’s syndrome, or endogenous hypercortisolemia, is a rare condition that both general practice clinicians and endocrinologists should be prepared to diagnose and treat. Including both the pituitary and adrenal forms of the disease, the Endocrine Society estimates that the disorder affects 10 to 15 people per million every year in the United States. It is more common in women and occurs most often in people between the ages of 20 and 50.

Even though Cushing’s remains a rare disease, cortisol recently made waves at the American Diabetes Association 84th Scientific Session. A highlight of the meeting was the initial presentation of data from the CATALYST trial, which assessed the prevalence of hypercortisolism in patients with difficult-to-control type 2 diabetes (A1c 7.5+).

CATALYST is a prospective, Phase 4 study with two parts. In the prevalence phase, 24% of 1,055 enrolled patients had hypercortisolism, defined as an overnight dexamethasone suppression test (ODST) value greater than 1.8 µg/dL and dexamethasone levels greater than 140 µg/dL. Results of CATALYST’s randomized treatment phase are expected in late 2024.

Elena Christofides, MD, FACE, founder of Endocrinology Associates, Inc., in Columbus, OH, believes the CATALYST results will be a wake-up call for both physicians and patients seeking to advocate for their own health. “This means that nearly 1 in 4 patients with type 2 diabetes have some other underlying hormonal/endocrine dysfunction as the reason for their diabetes, or significant contribution to their diabetes, and they should all be screened,” she said. “All providers need to get comfortable with diagnosing and treating hypercortisolemia, and you need to do it quickly because patients are going to pay attention as well.”

In Dr. Christofides’ experience, patients who suspect they have a hormonal issue may start with their primary care provider or they may self-refer to an endocrinologist. “A lot of Cushing’s patients are getting diagnosed and treated in primary care, which is completely appropriate. But I’ve also met endocrinologists who are uncomfortable diagnosing and managing Cushing’s because it is so rare,” she said. “The important thing is that the physician is comfortable with Cushing’s or is willing to put in the work get comfortable with it.”

According to Dr. Christofides, the widespread popular belief that “adrenal fatigue” is causing millions of Americans to feel sick, tired, and debilitated may be creating barriers to care for people who may actually have Cushing’s. “As physicians, we know that adrenal fatigue doesn’t exist, but we should still be receptive to seeing patients who raise that as a concern,” said Dr. Christofides. “We need to acknowledsalige their lived experience as being very real and it can be any number of diseases causing very real symptoms. If we don’t see these patients, real cases of hypercortisolemia could be left undiagnosed and untreated.”

Dr. Christofides, who also serves as a MedCentral Editor-at-Large, said she reminds colleagues that overnight dexamethasone suppression test (ODST) should always be the first test when you suspect Cushing’s. “While technically a screening test, the ODST can almost be considered diagnostic, depending on how abnormal the result is,” she noted. “But I always recommend that you do the ODST, the ACTH, a.m. cortisol, and the DHEAS levels at the same time because it allows you to differentiate more quickly between pituitary and adrenal problems.”

Dr. Christofides does see a place for 24-hour urine collection and salivary cortisol testing at times when diagnosing and monitoring patients with Cushing’s. “The 24-hour urine is only positive in ACTH-driven Cushing’s, so an abnormal result can help you identify the source, but too many physicians erroneously believe you can’t have Cushing’s if the 24-hour urine is normal,” she explained. “Surgeons tend to want this test before they operate and it’s a good benchmark for resolution of pituitary disease.” She reserves salivary cortisol testing for cases when the patient’s ODST is negative, but she suspects Cushing’s may be either nascent or cyclical.

Surgical resection has long been considered first-line treatment in both the pituitary and adrenal forms of Cushing’s. For example, data shared from Massachusetts General Hospital showed that nearly 90% of patients with microadenomas did not relapse within a 30-year period. A recent study found an overall recurrence rate of about 25% within a 10-year period. When reoperation is necessary, remission is achieved in up to 80% of patients.

As new medications for Cushing’s syndrome have become available, Dr. Christofides said she favors medical intervention prior to surgery. “The best part about medical therapy is you can easily stop it if you’re wrong,” she noted. “I would argue that every patient with confirmed Cushing’s deserves nonsurgical medical management prior to a consideration of surgery to improve their comorbidities and surgical risk management, and give time to have a proper informed consent discussion.”

In general, medications to treat Cushing’s disease rely on either cortisol production blockade or receptor blockade, said Dr. Christofides. Medications that directly limit cortisol production include ketoconazole, osilodrostat (Isturisa), mitotane (Lysodren), levoketoconazole (Recorlev), and metyrapone (Metopirone). Mifepristone (Korlym, Mifeprex) is approved for people with Cushing’s who also have type 2 diabetes to block the effects of cortisol. Mifepristone does not lower the amount of cortisol the body makes but limits its effects. Pasireotide (Signifor) lowers the amount of ACTH from the tumor. Cabergoline is sometimes used off-label in the US for the same purpose.

Following surgery, people with Cushing’s need replacement steroids until their adrenal function resumes, when replacement steroids must be tapered. But Dr. Christofides said she believes that all physicians who prescribe steroids should have a clear understanding of when and how to taper patients off steroids.

“Steroid dosing for therapeutic purposes is cumulative in terms of body exposure and the risk of needing to taper. A single 2-week dose of steroids in a year does not require a taper,” she said. “It’s patients who are getting repeated doses of more than 10 mg of prednisone equivalent per day for 2 or more weeks multiple times per year who are at risk of adrenal failure without tapering.”

Physicians often underestimate how long a safe, comfortable taper can take, per Dr. Christofides. “It takes 6 to 9 months for the adrenals to wake up so if you’re using high-dose steroids more frequently, that will cause the patient to need more steroids more frequently,” she explained. “If you’re treating an illness that responds to steroids and you stop them without tapering, the patient’s disease will flare, and then a month from then to 6 weeks from then you’ll be giving them steroids again, engendering a dependence on steroids by doing so.”

When developing a steroid taper plan for postoperative individuals with Cushing’s (and others), Dr. Christofides suggests basing it on the fact that 5 mg of prednisone or its equivalent is the physiologic dose. “Reduce the dose by 5 mg per month until you get to the last 5 mg, and then you’re going to reduce it by 1 mg monthly until done,” she said. “If a patient has difficulty during that last phase, consider a switch to hydrocortisone because a 1 mg reduction of hydrocortisone at a time may be easier to tolerate.”

Prednisone, hydrocortisone, and the other steroids have different half-lives, so you’ll need to plan accordingly, adds Dr. Christofides. “If you do a slower taper using hydrocortisone, the patient might feel worse than with prednisone unless you prescribe it BID.” She suggests thinking of the daily prednisone equivalent of hydrocortisone as 30 mg to allow for divided dosing, rather than the straight 20 mg/day conversion often used.

What happens after a patient’s Cushing’s has been successfully treated? Cushing’s is a chronic disease, even in remission, Dr. Christofides emphasized. “Once you have achieved remission, my general follow-up is to schedule visits every 6 months to a year with scans and labs, always with the instruction if the patient feels symptomatic, they should come in sooner,” she said.

More on Cushing’s diagnosis and therapies.

https://www.medcentral.com/endocrinology/cushings-syndrome-a-clinical-update

Filed under: adrenal, adrenal crisis, Cushing's, Diagnostic Testing, pituitary, Treatments | Tagged: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , | Leave a comment »

Is Cushing Syndrome More Common in the US Than We Think?

Posted on June 11, 2024 by MaryO

I think members of the Cushing’s Help boards have been saying this forever!  Cushing’s isn’t all that rare.  Just rarely diagnosed,

 

BOSTON — The prevalence of Cushing syndrome (CS) in the United States may be considerably higher than currently appreciated, new data from a single US institution suggest.

In contrast to estimates of 1 to 3 cases per million patient-years from population-based European studies, researchers at the University of Wisconsin, Milwaukee, estimated that the incidence of CS in Wisconsin is a minimum of 7.2 cases per million patient-years. What’s more, contrary to all previous studies, they found that adrenal Cushing syndrome was more common than pituitary adrenocorticotropic hormone (ACTH)– secreting tumors (Cushing disease), and that fewer than half of individuals with adrenal Cushing syndrome had classic physical features of hypercortisolism, such as weight gain, round face, excessive hair growth, and stretch marks.

“Cases are absolutely being missed…. Clinicians should realize that cortisol excess is not rare. It may not be common, but it needs to be considered in patients with any constellation of features that are seen in cortisol excess,” study investigator Ty B. Carroll, MD, Associate Professor of Medicine, Endocrinology and Molecular Medicine, and the Endocrine Fellowship Program Director at Medical College of Wisconsin in Milwaukee, told Medscape Medical News.

There are several contributing factors, he noted, “including the obesity and diabetes epidemics which make some clinical features of cortisol excess more common and less notable. Providers get used to seeing patients with some features of cortisol excess and don’t think to screen. The consequence of this is more difficult-to-control diabetes and hypertension, more advance metabolic bone disease, and likely more advanced cardiovascular disease, all resulting from extended exposure to cortisol excess,” he said.

Are Milder Cases the Ones Being Missed?

Asked to comment, session moderator Sharon L. Wardlaw, MD, professor of medicine at Columbia University College of Physicians and Surgeons, New York City, said “When we talk about Cushing [syndrome], we usually think of pituitary ACTH as more [common], followed by adrenal adenomas, and then ectopic. But they’re seeing more adrenal adenoma…we are probably diagnosing this a little more now.”

She also suggested that the Wisconsin group may have a lower threshold for diagnosing the milder cortisol elevation seen with adrenal Cushing syndrome. “If you screen for Cushing with a dexamethasone suppression test…[i]f you have autonomous secretion by the adrenal, you don’t suppress as much…. When you measure 24-hour urinary cortisol, it may be normal. So you’re in this in-between [state]…. Maybe in Wisconsin they’re diagnosing it more. Or, maybe it’s just being underdiagnosed in other places.”

She also pointed out that “you can’t diagnose it unless you think of it. I’m not so sure that with these mild cases it’s so much that it’s more common, but maybe it’s like thyroid nodules, where we didn’t know about it until everybody started getting all of these CT scans. We’re now seeing all these incidental thyroid nodules…I don’t think we’re missing florid Cushing.”

However, Wardlaw said, it’s probably worthwhile to detect even milder hypercortisolism because it could still have long-term damaging effects, including osteoporosis, muscle weakness, glucose intolerance, and frailty. “You could do something about it and normalize it if you found it. I think that would be the reason to do it.”

Is Wisconsin Representative of Cushing Everywhere?

Carroll presented the findings at the annual meeting of the Endocrine Society. He began by noting that most of the previous CS incidence studies, with estimates of 1.2-3.2 cases per million per year, come from European data published from 1994 to 2019 and collected as far back as 1955. The method of acquisition of patients and the definitions of confirmed cases varied widely in those studies, which reported CS etiologies of ACTH-secreting neoplasms (pituitary or ectopic) in 75%-85% and adrenal-dependent cortisol excess in 15%-20%.

The current study included data from clinic records between May 1, 2017, and December 31, 2022, of Wisconsin residents newly diagnosed with and treated for CS. The CS diagnosis was established with standard guideline-supported biochemical testing and appropriate imaging. Patients with exogenous and non-neoplastic hypercortisolism and those who did not receive therapy for CS were excluded.

A total of 185 patients (73% female, 27% male) were identified from 27 of the total 72 counties in Wisconsin, representing a population of 4.5 million. On the basis of the total 5.9 million population of Wisconsin, the incidence of CS in the state works out to 7.2 cases per million population per year, Carroll said.

However, data from the Wisconsin Hospital Association show that the University of Wisconsin’s Milwaukee facility treated just about half of patients in the state who are discharged from the hospital with a diagnosis of CS during 2019-2023. “So…that means that an actual or approximate incidence of 14-15 cases per million per year rather than the 7.2 cases that we produce,” he said.

Etiologies were 60% adrenal (111 patients), 36.8% pituitary (68 patients), and 3.2% ectopic (6 patients). Those proportions were similar between genders.

On biochemical testing, values for late-night salivary cortisol, dexamethasone suppression, and urinary free cortisol were highest for the ectopic group (3.189 µg/dL, 42.5 µg/dL, and 1514.2 µg/24 h, respectively) and lowest for the adrenal group (0.236 µg/dL, 6.5 µg/dL, and 64.2 µg/24 h, respectively). All differences between groups were highly statistically significant, at P < .0001, Carroll noted.

Classic physical features of CS were present in 91% of people with pituitary CS and 100% of those ectopic CS but just 44% of individuals with adrenal CS. “We found that adrenal-dependent disease was the most common form of Cushing syndrome. It frequently presented without classic physical features that may be due to the milder biochemical presentation,” he concluded.

Carroll reports consulting and investigator fees from Corcept Therapeutics. Wardlaw has no disclosures. 

Miriam E. Tucker is a freelance journalist based in the Washington DC area. She is a regular contributor to Medscape, with other work appearing in The Washington Post, NPR’s Shots blog, and Diatribe. She is on X (formerly Twitter) @MiriamETucker.

1

Credit

Lead image: Designer491/Dreamstime

Medscape Medical News © 2024 WebMD, LLCSend comments and news tips to news@medscape.net.

Cite this: Is Cushing Syndrome More Common in the US Than We Think? – Medscape – June 07, 2024.

Filed under: adrenal, Cushing's, pituitary, Rare Diseases, symptoms | Tagged: , , , , , , , , , | Leave a comment »

Epigenetic Mechanisms Modulated by Glucocorticoids With a Focus on Cushing Syndrome

Posted on April 19, 2024 by MaryO

Abstract

In Cushing syndrome (CS), prolonged exposure to high cortisol levels results in a wide range of devastating effects causing multisystem morbidity. Despite the efficacy of treatment leading to disease remission and clinical improvement, hypercortisolism-induced complications may persist. Since glucocorticoids use the epigenetic machinery as a mechanism of action to modulate gene expression, the persistence of some comorbidities may be mediated by hypercortisolism-induced long-lasting epigenetic changes. Additionally, glucocorticoids influence microRNA expression, which is an important epigenetic regulator as it modulates gene expression without changing the DNA sequence. Evidence suggests that chronically elevated glucocorticoid levels may induce aberrant microRNA expression which may impact several cellular processes resulting in cardiometabolic disorders.

The present article reviews the evidence on epigenetic changes induced by (long-term) glucocorticoid exposure. Key aspects of some glucocorticoid-target genes and their implications in the context of CS are described. Lastly, the effects of epigenetic drugs influencing glucocorticoid effects are discussed for their ability to be potentially used as adjunctive therapy in CS.

epigenetic, glucocorticoids, Cushing syndrome
Issue Section:

Mini-review

In Cushing syndrome (CS), adrenocorticotropic hormone (ACTH) hypersecretion by a pituitary adenoma or an ectopic source, or autonomous cortisol hypersecretion by an adrenal tumor, induces chronic endogenous hypercortisolism with loss of the cortisol circadian rhythm (1). CS is more prevalent in women than men and frequently occurs in the fourth to sixth decades of life (2).

Glucocorticoids (GC) have extensive physiological actions and regulate up to 20% of the expressed genome, mainly related to the immune system, metabolic homeostasis, and cognition. Therefore, the prolonged exposure to high cortisol levels results in a wide range of devastating effects, including major changes in body composition (obesity, muscle atrophy, osteoporosis), neuropsychiatric disturbances (impaired cognition, depression, sleep disturbances), the metabolic syndrome (obesity, hypertension, insulin resistance, and dyslipidemia), hypercoagulability, and immune suppression (3, 4). The consequences of hypercortisolism lead to compromised quality of life and increased mortality rate (5). The mortality rate in patients with CS is 4 times higher than the healthy control population (6). Risk factors such as obesity, diabetes, and hypertension contribute to the increased risk of myocardial infarction, stroke, and cardiac insufficiency. As a result, cardiovascular disease is the leading cause of the premature death in CS (5). Infectious disease is also an important cause of death in CS (5). Therefore, prompt treatment to control hypercortisolism is imperative to prevent complications and an increased mortality rate.

Despite the efficacy of treatment leading to disease remission, the clinical burden of CS improves, but does not completely revert, in every patient (7). Indeed, obesity, neuropsychiatric disturbances, hypertension, diabetes, and osteoporosis persist in a substantial number of biochemically cured patients. For instance, in a study involving 118 CS patients in remission for about 7.8 years (median), resolution of comorbidities such as diabetes occurred in only 36% of cases, hypertension in 23% of cases, and depression in 52% of the cases (8). It has been proposed that epigenetic changes as a consequence of hypercortisolism is a mechanism of the persistence of some comorbidities (9-12).

Epigenetics is a reversible process that modifies gene expression without any alterations in DNA sequence; frequently it is mediated by histone modification and DNA methylation together with microRNAs (13-15). GCs use the epigenetic machinery as a mechanism of action to regulate gene expression in physiological circumstances, such as metabolic actions and stress response. Its networks involve DNA and histone modifying enzymes, such as DNA methyltransferases (DNMTs), histone acetyltransferases (HATs), and histone deacetylases (HDACs) (16). (Fig. 1) The DNA methylation process catalyzed by DNMTs is usually associated with downregulation of gene expression (17). Histone modifications catalyzed by HAT enzymes induce gene transcription, while those by HDAC enzymes induce transcriptional repression (17). Drugs interfering with these enzymes (so-called epigenetic drugs) may affect the GC genomic actions confirming the interaction between GC and the epigenetic system (18, 19). Furthermore, GC can modulate HDAC and DNMT expression and activity (16, 19, 20). Based on these data it might be speculated that in CS, epigenetic modifications induced by long-term GC exposure plays a role in the development of the disease-specific morbidity (9, 10).

Figure 1.
Glucocorticoid (GC) and its epigenetic machinery. GC through its receptor interacts with DNA and histone modifying enzymes, such as DNA methyltransferases (DNMTs), histone acetyl transferases (HATs), and histone deacetylases (HDAC) to modulate gene expression.

Open in new tabDownload slide

Glucocorticoid (GC) and its epigenetic machinery. GC through its receptor interacts with DNA and histone modifying enzymes, such as DNA methyltransferases (DNMTs), histone acetyl transferases (HATs), and histone deacetylases (HDAC) to modulate gene expression.

In this review we provide an overview of epigenetic aspects of GC action in physiological conditions and in the context of CS. We start with a detailed characterization of how GC, using the epigenetic system, can change chromatin structure in order to activate or silence gene expression. (Fig. 2) Subsequently, we describe the role of epigenetic mechanisms in the regulation of expression of several GC-target genes related to CS. Finally, we present the current evidence of epigenetic changes caused by the long-term of GC exposure and the potential use of epidrugs influencing GC actions.

Figure 2.
Epigenetic mechanisms of the glucocorticoid action to regulate gene expression. The GR is located in cytoplasm in a multi-protein complex; after GC binding, GR dissociates from the multi-protein complex, crosses the nuclear membrane, dimerizes, and binds to the GRE of the target gene. One of the mechanisms of action of GC is through the recruitment of co-regulators together with epigenetic enzymes, such as HAT, to change the chromatin structure, resulting in activation of gene transcription. Also, GR decreases gene expression by tethering other transcriptional factors and recruiting HDAC2, causing histone deacetylation, which leads to a repressed chromatin. GC can cause hypomethylation through downregulation in the expression of DNMT1. Abbreviations: Ac, acetylation; DNMT1, DNA methyltransferase 1; GC, glucocorticoid; GR, glucocorticoid receptor; GRE, glucocorticoid responsive elements; HAT, histone acetyltransferase; HDAC, histone deacetylases; Me: methylation.

Open in new tabDownload slide

Epigenetic mechanisms of the glucocorticoid action to regulate gene expression. The GR is located in cytoplasm in a multi-protein complex; after GC binding, GR dissociates from the multi-protein complex, crosses the nuclear membrane, dimerizes, and binds to the GRE of the target gene. One of the mechanisms of action of GC is through the recruitment of co-regulators together with epigenetic enzymes, such as HAT, to change the chromatin structure, resulting in activation of gene transcription. Also, GR decreases gene expression by tethering other transcriptional factors and recruiting HDAC2, causing histone deacetylation, which leads to a repressed chromatin. GC can cause hypomethylation through downregulation in the expression of DNMT1. Abbreviations: Ac, acetylation; DNMT1, DNA methyltransferase 1; GC, glucocorticoid; GR, glucocorticoid receptor; GRE, glucocorticoid responsive elements; HAT, histone acetyltransferase; HDAC, histone deacetylases; Me: methylation.

Search Strategy

A search of the PubMed database was conducted using the advanced search builder tool for articles in the English language on the following terms “glucocorticoids,” “glucocorticoid receptor,” “Cushing,” “hypercortisolism,” “epigenetic,” “DNA methylation,” “histone deacetylase,” “histone acetyltransferase,” “microRNA” “fkbp5,” “clock genes,” and “POMC.” Moreover, references were identified directly from the articles included in this manuscript. The articles were selected by the authors after being carefully analyzed regarding their importance and impact.

Epigenetic Aspects of Genomic Action of Glucocorticoids

GCs regulate gene expression positively or negatively. GC-responsive genes include genes encoding for proteins associated with inflammation, metabolic processes, blood pressure and fluid homeostasis, apoptosis, cell cycle progression, circadian rhythm, and intracellular signaling (21).

The GC actions are cell type–specific (22). For instance, in an in vitro study, the comparison of GC-expressed genes between 2 cell lines, corticotroph (AtT20) and mammary (3134) cell lines, showed a different set of GC-regulated genes, revealing the cell type–specific nature of GC effects (23). GC function depends on the accessibility of glucocorticoid receptor (GR)-binding sites in the DNA of the target tissue, which in turn is mostly established during cell differentiation. Therefore, different chromatin organization explains the distinct GR-binding sites among different tissues (22, 24, 25). The chromatin accessibility is determined by histone modifications such as acetylation, methylation, phosphorylation, and/or DNA methylation, processes that are both dynamic and reversible (26).

Furthermore, gene expression is regulated in a GC-concentration-dependent manner which is tissue-specific. Only a few genes can be upregulated or downregulated at low concentrations of GC. For example, a dose of dexamethasone (Dex) as low as 0.5 nM selectively activated PER1 (period 1, transcription factor related to circadian rhythm) expression in lung cancer (A549) cells (21, 27). Additionally, continuous GC exposure or pulsed GC (cortisol fluctuation during circadian rhythm) may cause different responses with respect to gene expression (26, 28). For example, constant treatment with corticosterone induced higher levels of PER1 clock gene mRNA expression compared with pulsatile treatment, as demonstrated in an in vitro study using 3134 cell line (28).

The time course for gene expression in response to Dex is fast, with repression occurring slightly slower compared to activation. Half of activated and repressed genes are detected within, respectively, about 40 minutes and 53 minutes following Dex exposure (21).

In short, the transcriptional output in response to GC depends on cell type, as well as on the duration and intensity of GC exposure (21, 24, 26, 27). GCs act as a transcriptional regulatory factor resulting in activating or repressing the expression of genes. The GC exerts its function through binding to corticosteroid receptors, specifically, the mineralocorticoid receptor and the GR, members of the nuclear receptor superfamily (29, 30).

Glucocorticoid Receptor

The GR is located in the cytoplasm in a chaperone complex which includes heat-shock proteins (70 and 90) and immunophilins (such as FK506 binding protein [FKBP5]). Cortisol diffuses across the cell membrane and binds with high affinity to the GR. The activated GR bound to GC dissociates of the multi-protein complex and is transferred to the nucleus, where it ultimately regulates gene expression (26, 31).

GR is a transcription factor encoded by nuclear receptor subfamily 3, group C member 1 (NR3C1) gene, located in chromosome 5, and consisting of 9 exons. It is composed of 3 major functional domains, namely a DNA binding domain (DBD), the C-terminal ligand-binding domain (LBD) and the N-terminal domain (NTB). The LBD recognizes and joins the GC. NTB contains an activation function-1 (AF1) which connects with co-regulators and the members of the general transcription machinery to activate target genes. The DBD comprises 2 zinc fingers motifs that are able to identify and bind to glucocorticoid responsive elements (GREs) (32, 33).

GRα is the most expressed and functionally active GR. GRβ is another isoform which is the result of an alternative splicing in exon 9 of the GR transcript. The difference between the 2 isoforms is the distinct ligand-binding domain in GRβ. This variance prevents the GRβ from binding to GC. In fact, the GRβ counteracts GRα function by interfering with its binding to a GRE in the target gene, and GRβ expression is associated with GC resistance (32). In addition, GRβ has its own transcriptional activity which is independent and distinct from GRα (34).

Another splice variant of human GR, GRγ, is associated with GC resistance in lung cell carcinoma and childhood acute lymphoblastic leukemia (33, 35). There is an additional amino acid (arginine) in the DBD of the GRγ that reduces, by about half, the capacity to activate or suppress the transcription of the target gene, as compared with GRα (32). One study identified GRγ in a small series of corticotroph adenomas (36).

Glucocorticoid Mechanism of Action

The GR-GC complex induces or represses gene expression directly by binding to DNA, indirectly by tethering other transcription factors or yet in a composite manner that consists in binding DNA in association with binding to other co-regulators (35, 37).

The GR has the ability to reorganize the chromatin structure to become more or less accessible to the transcriptional machinery. In the classical mechanism of direct induction of gene expression, the GR dimerizes and binds to a GRE in DNA. The receptor recruits co-regulators, such as CREB binding protein, which has intrinsic histone acetyltransferase (HAT) activity that modifies the chromatin structure from an inactive to an active state. This model, called transactivation, upregulates the expression of some genes related to glucose, protein, and fat metabolism. Gene repression, on the other hand, is accomplished by GR binding to a negative GRE (nGRE) leading to the formation of a chromatin remodeling complex composed by co-repressor factors, such as NCOR1 and SMRT, and histone deacetylases (HDACs), that ultimately turn chromatin less accessible and suppress gene transcription. The gene repression through direct binding events occurs less frequently when compared to gene induction (25, 35, 38).

Another mechanism of GC action is through binding to other transcription factors (tethering). In case of switching off inflammatory genes, GR binds to transcriptional co-activator molecules, such as CREB binding protein with intrinsic HAT activity, and subsequently recruits HDAC2 to reverse histone acetylation, thus resulting in a suppression of the activated inflammatory gene (39). In the same model, GC interacts with other cofactors, such as the STAT family, to induce chromatin modifications resulting in increased gene expression (26).

Furthermore, the transcriptional dynamics of some genes follow a composite manner. In this model, GR, in conjunction with binding to GRE, also interacts with cofactors in order to enhance or reduce gene expression (35).

GCs can also modulate gene expression by influencing the transcription of epigenetic modifiers. An experimental study demonstrated that GC mediated the upregulation of HDAC2 in rats exposed to chronic stress, which in turn decreased the transcription of histone methyltransferase (Ehmt2) that ultimately upregulated the expression of Nedd4. Nedd4 is a ubiquitin ligase, expression of which has been related to cognitive impairment (40). Additionally, GC was found to interact with another epigenetic eraser, namely JMJD3, a histone demethylase, suppressing its transcription in endothelial cells treated with TNFα that led to decreased expression of other genes related to the blood-brain barrier (41).

GCs have the ability to induce (de)methylation changes in DNA, ultimately affecting gene expression. The DNA methylation process triggered by GC involves the family of DNA methyltransferases (DNMT) and ten-eleven translocation (TET) protein (20, 42-44). The DNMT, DNMT1, DNMT3A, and DNMT3B are able to transfer a methyl group to a cytosine residue in DNA, forming 5-methylcytosine (5mC), which negatively impacts gene expression. In contrast, TET protein chemically modifies the 5mC to form 5-hydroxymethylcytosine (5hmC), which ultimately leads to unmethylated cytosine, positively influencing gene expression (45).

Glucocorticoids mainly induce loss of methylation events rather than gain of methylation across the genome (11, 46). The DNA demethylation process can be either active or passive. The active mechanism is linked to the upregulation of TET enzyme expression that follows GC treatment, which was described in retinal and osteocyte cell line model studies (42, 43). The passive demethylation event involves the downregulation (Fig. 2) or dysfunction of DNMT1. DNMT1 is responsible for maintaining the methylation process in dividing cells (45). In case of GC exposure, GC can cause hypomethylation through downregulation in the expression of DNMT1, a process described in the AtT20 corticotroph tumor cell model, or through GC hindering DNMT activity, particularly DNMT1, as demonstrated in the retinal cell (RPE) line (20, 42, 44).

Glucocorticoid-Induced Epigenetic Changes

There are several molecular mechanisms connecting GR activation and epigenetic modifications ultimately affecting gene expression (Fig. 2). As described above, GC uses epigenetic machinery, such as DNA and histone modifying enzymes, to restructure the chromatin in order to induce or silence gene transcription (16, 47).

In an in vitro study using murine AtT20 corticotroph tumor and neuronal cell lines, after chronic GC exposure followed by a recovery period in the absence of GC, the cells retained an “epigenetic memory” with persistence of loss of methylation content in FKBP5 gene but with no increased gene expression at baseline. The functionality of this “epigenetic memory” only became evident in a second exposure to GC, when the cells responded sharply with a more robust expression of FKBP5 gene compared to the cells without previous exposure to GC (44). Another in vitro study, using a human fetal hippocampal cell line, confirmed long-lasting DNA methylation changes induced by GC. The cells were treated for 10 days with dexamethasone, during the proliferative and cell differentiation phases of the cell line, followed by 20 days without any treatment. The second exposure to GC resulted in an enhanced gene expression of a subset of GC-target genes (48). Additionally, using an animal model subjected to chronic stress, a distinct gene expression profile was demonstrated in response to acute GC challenge compared to those without chronic stress history. The proposed mechanism was that chronic stress resulted in GC-induced enduring epigenetic changes in target genes, altering the responsiveness to a subsequent GC exposure (49).

In general, it seems that the majority of differential methylation regions (DMRs) induced by GC are loss of methylation rather than gain of methylation. In an experimental study, an association between hypomethylation and GC exposure was demonstrated in mice previously exposed to high levels of GC. Further analysis demonstrated that the genes linked with DMR were mostly related to metabolism, the immune system, and neurodevelopment (11).

Human studies have also shown that excess of cortisol can induce modifications in DNA methylation. DNA methylation data obtained from whole blood samples from patients with chronic obstructive pulmonary disease (COPD) treated with GC revealed DMR at specific CpG dinucleotides across the genome. These DMR were confirmed by pyrosequencing and annotated to genes, such as SCNN1A, encoding the α subunit of the epithelial sodium channel, GPR97, encoding G protein coupled receptor 97, and LRP3, encoding low-density lipoprotein receptor-related protein 3 (50). Furthermore, it has been proposed that the negative impact of chronic GC exposure on the immune system, which increases the risk of opportunistically infections, may be epigenetically mediated (51). In a clinical study, using whole blood samples, an analysis of genome-wide DNA methylation was performed on patients before and after exposure to GC (51). Long-term GC exposure disrupts, through a persistent modification of the cytosine methylation pattern, the mTORC1 pathway which affects CD4+ T cell biology (51).

Taken together, these data clearly show the interplay between GC signaling and methylation and histone modifications processes suggesting that GC interferes in the epigenetic landscape modulating gene expression. It is possible that most of these GC-induced epigenetic events are dynamic and temporary, while others may persist leading to long-lasting disorders. Further research to provide insight into what makes some events reversible is warranted.

Epigenetic Changes as a Consequence of Long-Term Glucocorticoid Exposure in Cushing Syndrome

The comorbidities associated with CS are associated with increased mortality mainly due to cardiovascular events (52). GC-induced comorbidities in CS may be at least in part epigenetically mediated. Previous study using whole blood methylation profile demonstrated that specific hypomethylated CpG sites induced by GC were associated with Cushing comorbidities, such as hypertension and osteoporosis (46). The study identified a methylator predictor of GC excess which could be used as a biomarker to monitor GC status (46).

The long-term exposure to high cortisol levels may be crucial for the persistence of some morbidities in CS through epigenetic changes. Hypercortisolism-induced persistent changes in visceral adipose tissue gene expression through epigenetic modifications was investigated in a translational study (12). This study combined data from patients with active CS and data from an animal model of CS in active and remitted phase. Interestingly, the study demonstrated long-lasting changes in the transcriptome of adipose tissue that were associated with histone modifications induced by GC. Therefore, these epigenetic fingerprints observed even after the resolution of hypercortisolism may elucidate the mechanism of persistent modifications in gene expression in the visceral adipose tissue (12).

With regard to the persistence of GC-induced DMR, a genome-wide DNA methylation analysis showed a lower average of DNA methylation in patients in remission of CS compared to controls. Interestingly, the most common biologically relevant affected genes were retinoic acid receptors, thyroid hormone receptors, or hormone/nuclear receptors, important genes related to intracellular pathways and regulators of gene expression (9).

In summary, this large body of evidence supports the concept that prolonged GC exposure modulates the epigenetic landscape across the genome by inducing DMR and histone modifications. Some epigenetic modifications are persistent, and this may partially explain the incomplete reversibility of some of CS features following clinical remission.

Glucocorticoid-Target Genes in Cushing Syndrome

A detailed identification and characterization of GC-target genes may shed light in the understanding of the pathophysiology and treatment response in patients with CS. For instance, the GC regulation of pro-opiomelanocortin (POMC) expression as part of the physiologic GC negative feedback may be impaired in Cushing disease (CD), which is an important mechanism for the maintenance of high GC levels (53). Another example is the interaction between GC and clock genes, which may interfere in the loss of the GC circadian rhythm and may contribute to metabolic disorders in CS (54). Furthermore, the suppressive action of GC on drug targets, such as the somatostatin receptor (subtype 2), may influence the efficacy of first-generation somatostatin receptor ligands in normalizing cortisol levels in CD (55). Here we describe how GCs using epigenetic machinery influence the expression of important target genes and their implications in CS.

FKBP5

FK506 binding protein (FKBP5) plays an important role in the regulation of hypothalamic-pituitary-adrenal (HPA) system (56). As part of the GC negative feedback loop, GC binds to hypothalamic and pituitary GR. In the cytoplasm, GR is bound to a multi-protein complex including FKBP5. FKBP5 modulates GR action by decreasing GR binding affinity to GC and by preventing GR translocation from cytoplasm to nucleus (57, 58). In other words, an increase of FKBP5 expression is inversely correlated with GR activity and results in GC resistance leading to an impaired negative feedback regulation in the HPA axis (59).

FKBP5 is a GC-responsive gene; its upregulation by GC is part of an intracellular negative short-feedback loop (60). The mechanism by which GC regulates FKBP5 expression was shown to include inhibition of DNA methylation (44). In a model for CS, mice treated with corticosterone for 4 weeks had a reduced level of DNA methylation of FKBP5 in DNA extracted from whole blood, which was strongly correlated in a negative manner with GC concentration. Interestingly, a negative correlation was also observed between the degree of FKBP5 gene methylation measured at 4 weeks of GC exposure and the percentage of mice visceral fat (61). Accordingly, previous studies have provided compelling evidence of decreased methylation in the FKBP5 gene in patients with active CS compared to healthy control (10, 46). Even in patients with CS in remission, previous data have suggested a small decrease in FKBP5 methylation levels compared to healthy controls (9, 10). In an in vitro study, it was demonstrated that, by decreasing DNMT1 expression, GC is able to reduce FKBP5 methylation levels and, therefore, increase its expression (44).

Likewise, FKBP5 mRNA is also sensitive to GC exposure. A time-dependent increase in blood FKBP5 mRNA after single-dose prednisone administration has been demonstrated in healthy humans (62). Accordingly, patients with ACTH-dependent CS had higher blood FKBP5 mRNA levels compared with healthy controls, and after a successful surgery, FKBP5 mRNA returned to baseline levels (63). Furthermore, in another study, blood FKBP5 mRNA was inversely correlated with FKBP5 promoter methylation and positively correlated with 24-hour urine free cortisol (UFC) levels in patients with CS (46). Taken together, this fine-tuning of FKBP5 DNA methylation and mRNA according to the level of GC suggests that FKBP5 can be used as a biomarker to infer the magnitude of GC exposure.

POMC and Corticotropin-Releasing Hormone

The partial resistance of the corticotroph adenoma to GC negative feedback is a hallmark of CD. Indeed, the lack of this inhibitory effect constitutes a method to diagnose CD, that is, with the dexamethasone suppression test. One of the mechanisms related to the insensitivity to GC can be attributed to GR mutations which are, however, rarely found in corticotrophinomas (64). Another mechanism that was uncovered in corticotroph adenomas is an overexpression of the HSP90 chaperone resulting in reduced affinity of GR to its ligand and consequently GR resistance (53, 65).

In addition, the loss of protein expression of either Brg1, ATPase component of the SWI/SNF chromatin remodeling complex, or HDAC2 has been linked to GC resistance in about 50% of some adenomas (66). The trans-repression process on POMC transcription achieved by GC involves both the histone deacetylation enzyme and Brg1. One mechanism of corticotropin-releasing hormone (CRH)-induced POMC expression is through an orphan nuclear receptor (NR) related to NGFI-B (Nur77). NGFI-B binds to the NurRE sequence in the promoter region of POMC gene and recruits a co-activator to mediate its transcription. In a tethering mechanism, the GR directly interacts with NGFI-B to form a trans-repression complex, which contains the GR itself, Brg1, the nuclear receptor, and HDAC2; the latter being essential to block the gene expression through chromatin remodeling process (53, 66).

In CD, hypercortisolism exerts a negative feedback at CRH secretion from the hypothalamus (67). The mechanism involved in GR-induced suppression of CRH expression is through direct binding to a nGRE in the promoter region of CRH gene and subsequent recruitment of repressor complexes. In a rat hypothalamic cell line, it was demonstrated that Dex-induced CRH repression occurs through coordinated actions of corepressors involving Methyl-CpG-binding protein 2 (MeCP2), HDAC1, and DNA methyltransferase 3B (DNMT3B). Possibly, GR bound to nGRE recruits DNMT3B to the promoter in order to methylate a specific region, subsequently binding MeCP2 on these methylated sites followed by the recruitment of chromatin modify corepressor HDAC1, ultimately resulting in CRH suppression. Another possibility is that 2 independent complexes, one consisting of GR with DNMT3 for the methylation and the other the MeCP2, bound to methylated region, interact with HDAC1 to induce repression (68).

Clock Genes

The clock system and the HPA axis are interconnected regulatory systems. Cortisol circadian rhythm is modulated by the interaction between a central pacemaker, located in the hypothalamic suprachiasmatic nuclei, and the HPA axis (69). At the molecular level, mediators of the clock system and cortisol also communicate with each other, both acting as transcription factors of many genes to influence cellular functions.

In CS, the impact of chronic GC exposure on clock genes expression was recently evaluated using peripheral blood samples from patients with active disease compared with healthy subjects. The circadian rhythm of peripheral clock gene expression (CLOCK, BMAL, PER1-3, and CRY1) was abolished as a result of hypercortisolism, and that may contribute to metabolic disorders observed in Cushing patients (70). Another study, which investigated persistent changes induced by hypercortisolism in visceral adipose tissue, found that the expression of clock genes, such as PER1, remained altered in association with persistent epigenetic changes in both H3K4me3 and H3K27ac induced by hypercortisolism even after the resolution of hypercortisolism (12). This suggests that chronic exposure to GC may induce sustained epigenetic changes that can influence clock genes expression. Nevertheless, further studies are warranted to better elucidate how long-term exposure to GC impacts clock genes expression using the epigenetic machinery.

Glucocorticoid Effects on MicroRNAs

Along with histone modification and DNA methylation, microRNAs (miRNAs) have emerged as an epigenetic mechanism capable of impacting gene expression without changing DNA sequence (15). Interestingly, miRNA expression itself is also under the influence of epigenetic modifications through promoter methylation like any other protein-encoding genes (71).

MicroRNAs are small (about 20-25 nucleotides in length) non-coding RNAs that are important in transcriptional silencing of messenger RNA (mRNA). By partially pairing with mRNA, miRNAs can either induce mRNA degradation or inhibit mRNA translation to protein. MiRNAs regulate the translation of about 50% of the transcriptome, allowing them to play an important role in a wide range of biological functions, such as cell differentiation, proliferation, metabolism, and apoptosis under normal physiological and pathological situations. Some miRNAs can be classified as oncogenes or tumor suppressing genes, and aberrant expression of miRNAs may be implicated in tumor pathogenesis (71-73).

Insight into the regulation of miRNA expression is, therefore, crucial for a better understanding of tumor development and other human diseases, including cardiac, metabolic, and neurological disorders (73, 74). There are different regulatory mechanisms involved in miRNA expression, including transcriptional factors such as GR-GC. GC may modulate miRNA expression through direct binding to GRE in the promoter region of the host gene, as observed in hemopoietic tumor cells (75). In addition to transcriptional activation, in vascular smooth muscle cells, Dex treatment induces downregulation of DNMT1 and DNMT3a protein levels and reduces the methylation of miRNA-29c promoter, resulting in an increased expression of miRNA-29c (76). Interestingly, it was demonstrated that the increased expression of miRNA-29 family (miRNA-29a, -29b, and -29c) associates with metabolic dysfunction, such as obesity and insulin resistance, which pertains to CS (77, 78). With regard to metabolic dysfunction, miRNA-379 expression was shown to be upregulated by GC and its overexpression in the liver resulted in elevated levels of serum triglycerides associated with very low-density lipoprotein (VLDL) fraction in mice (79). In obese patients, the level of hepatic miRNA-379 expression was higher compared to nonobese patients and positively correlated with serum cortisol and triglycerides (79). Hence, GC-responsive miRNA may be, at least in part, a mediator to GC-driven metabolic conditions in CS.

In pathological conditions, such as seen in CS, prolonged exposure to an elevated cortisol level results in a wide range of comorbidities. It can be hypothesized that the chronic and excessive glucocorticoid levels may induce an aberrant miRNA expression that might impact several cellular processes related to bone and cardiometabolic disorders. A recent study addressed the impact of hypercortisolism on bone miRNA of patients with active CD compared to patients with nonfunctional pituitary adenomas. Significant changes in bone miRNA expression levels were observed, suggesting that the disruption of miRNA may be partially responsible for reduced bone formation and osteoblastogenesis (80). Similarly, altered expression levels of selected miRNAs related to endothelial biology in patients with CS may point to a contribution to a high incidence of cardiovascular disorders in Cushing patients (81). Therefore, dysregulated miRNAs as a consequence of high cortisol levels may underpin the development and progression of comorbidities related to CS. To the best of our knowledge, it is currently not clear whether miRNA dysregulation persists after resolution of hypercortisolism, thus contributing to the persistence of some comorbidities. This hypothesis needs to be further investigated.

MicroRNA can also be used as a diagnostic tool in CS. A study was performed to identify circulating miRNA as a biomarker to differentiate patients with CS from patients with suspected CS who had failed diagnostic tests (the control group) (82). It was observed that miRNA182-5p was differentially expressed in the CS cohort compared to the control group; therefore, it may be used as a biomarker (82). However, a large cohort is necessary to validate this finding (82). In corticotroph tumors, downregulation of miRNA 16-1 expression was observed relative to normal pituitary tissue (83). In contrast, the plasma level of miRNA16-5p was found to be significantly higher in CD compared to ectopic Cushing (EAS) and healthy controls (84). This finding suggests that miRNA16-5p may be a biomarker capable to differentiate the 2 forms of ACTH-dependent Cushing (84).

Epidrugs and Glucocorticoid Action in Cushing’s Syndrome

The interest in understanding the epigenetic mechanism of GC action in the context of CS is based on reversibility of epi-marks, such as DNA methylation and histone modifications, using epidrugs (85, 86). The biological characteristics of epigenetic drugs and their target have been extensively explored. Their effectiveness as antitumor drugs have been tested on corticotroph tumors using in vitro studies (87-89). However, a limited number of studies have explored the role of epidrugs as a therapeutic tool in reversing the genomic action of GC in CS, particularly in comorbidities induced by hypercortisolism (90, 91).

The use of histone deacetylase inhibitors (HDACi) may reduce the genomic action of GC (90-92). It has been demonstrated that the use of the HDAC inhibitor valproic acid increases the acetylation level of GR, consequently attenuating the genomic action of GC. In an experimental Cushing model in rats, the use of valproic acid decreased expression of genes related to lipogenesis, gluconeogenesis, and ion regulators in the kidney that ultimately reduces hepatic steatosis, hyperglycemia, and hypertension in ACTH-infused rats (90, 91).

More studies evaluating the effects of epidrugs influencing the GC actions are warranted to further elucidate the underlying mechanisms and to explore potential treatment modalities to reverse long-lasting consequences of chronic corticoid exposure.

Conclusions

In physiologic conditions, GC are secreted in pulses following a circadian rhythm pattern, as opposed to a constant, chronic, and high GC exposure in CS. This pathological pattern may account for numerous devastating effects observed in CS (7). Yet, the expressed genome in response to chronic GC exposure may potentially be abnormal, leading to dysregulation in clock genes, among other effects.

GC levels may return to a normal circadian pattern in response to a successful treatment, but with incomplete reversibility of some CS features, which may in part be explained by epigenetic changes. The epigenetic machinery is used by GC to induce dynamic changes in chromatin to modulate gene expression. (Fig. 2) It seems that most of chromatin modifications are reversible, but some may persist resulting in long-term epigenetic changes. (Table 1)

Table 1.

Evidence of interaction between glucocorticoid and epigenetic machinery

Epigenetic changes/epigenetic enzymes Action
Histone acetylation (HAT)

  • Glucocorticoid receptors (GR) recruit co-regulators, such as CREB binding protein (CBP), which has intrinsic histone acetyltransferase (HAT) activity that modifies the chromatin structure from an inactive to an active state (25, 33, 35).
Histone deacetylation (HDAC)

  • GR recruit histone deacetylases (HDACs) to turn chromatin less accessible and suppress gene transcription (25, 35).

  • The trans-repression process on POMC transcription achieved by glucocorticoids (GC) involves the histone deacetylation enzyme (HDAC2).

  • GC mediates the upregulation of HDAC2 in rats exposed to chronic stress (40).
Histone demethylase (JMJD3)

  • GC suppress transcription of JMJD3 in endothelial cells treated with TNFα (41).
Histone modifications

  • Using ChIP-seq, a study in mice treated for 5 weeks with corticosterone showed higher levels of histone modifications (H3K4me3, H3K27ac) compared to control mice. In mice after a 10-week washout period, persistence of this epigenetic fingerprint was observed, which was associated with long-lasting changes in gene expression (12).
DNA methylation (DNMT3B) and histone deacetylation (HDAC1)

  • GC mediates CRH downregulation through DNMT3B to the promoter in order to methylate a specific region and recruitment of chromatin modify corepressor HDAC (68).
DNA hypomethylation

  • GC induces downregulation of DNMT1 in AtT20 (mouse corticotroph adenoma cell line) (20).

  • GC induces upregulation of TET enzyme expression which was described in retinal and osteocyte cell line model (42, 43).

  • An experimental study in mice previously exposed to high levels of GC showed differentially methylated regions (DMR) induced by GC treatment, of which the majority was loss of the methylation (11).

  • Reduced DNA methylation in FKBP5 gene was found in patients in active disease and also in remission state of Cushing syndrome (CS) as compared to a healthy control group (10).

  • A genome-wide DNA methylation analysis showed a lower average of DNA methylation in patients in remission of CS compared to controls (9).

  • A study using whole blood methylation profile demonstrated an association between cortisol excess and DNA hypomethylation in patients with CS (46).
Open in new tab

Further studies are needed to elucidate how chronic exposure to GC leads to incomplete reversibility of CS morbidities via sustained modulation of the epigenetic machinery and possibly other mechanisms. Subsequent identification of therapeutic targets may offer new perspective for treatments, for example, with epidrugs, aiming to reverse hypercortisolism-related comorbidities.

Funding

The authors received no financial support for this manuscript.

Disclosures

T.P., R.A.F., and L.J.H. have nothing to declare.

Data Availability

Data sharing is not applicable to this article, as no datasets were generated or analyzed during the current study.

From https://academic.oup.com/jcem/advance-article/doi/10.1210/clinem/dgae151/7633538?searchresult=1

Filed under: Cushing's, symptoms | Tagged: , , , , , , | Leave a comment »

Olfactory Neuroblastoma Causing Cushing’s Syndrome Due to the Ectopic Adrenocorticotropic Hormone (ACTH) Secretion

Posted on March 27, 2024 by MaryO

Abstract

Cushing’s syndrome is a constellation of features occurring due to high blood cortisol levels. We report a case of a 47-year-old male with a history of recurrent olfactory neuroblastoma (ONB). He presented with bilateral lower limb weakness and anosmia and was found to have Cushing’s syndrome due to high adrenocorticotropic hormone (ACTH) levels from an ectopic source, ONB in this case. Serum cortisol and ACTH levels declined after tumor removal.

Introduction

Olfactory neuroblastoma (ONB), or esthesioneuroblastoma, is a rare malignancy arising from neuroepithelium in the upper nasal cavity. It represents approximately 2% of all nasal passage tumors, with an incidence of approximately 0.4 per 2.5 million individuals [1]. ONB shares similar histological features with small round blue cell neoplasms of the nose. Ectopic hormone secretion is a very rare feature associated with these tumors. Five-year overall survival is reported to be between 60% and 80% [2,3]. The age distribution is either in the fifth to sixth decade of life [4,5], or in the second and sixth decades [6].

Features of Cushing’s syndrome (moon face, buffalo hump, central obesity hypertension, fragile skin, easy bruising, fatigue, muscle weakness) are due to high blood cortisol levels [7]. It can be either primary (cortisol-secreting adrenal tumor), secondary (adrenocorticotropic hormone (ACTH)-secreting pituitary tumor, also called Cushing disease), or ectopic ACTH secretion (from a non-pituitary source). All three types share similar features [8].

Ectopic ACTH syndrome (EAS) is due to an extra pituitary tumor, producing ACTH. It accounts for 12-17% of Cushing’s syndrome cases [9]. Most cases of EAS-producing tumors are in the lungs, mediastinum, neuroendocrine tumors of the gastrointestinal tract, and pheochromocytomas [9]. Ectopic ACTH secretion from an ONB is very rare. As of 2015, only 18 cases were reported in the literature [10]. Here, we report such a case.

Case Presentation

Our patient is a 47-year-old Bangladeshi male, with a history of recurrent ONB that was resected twice in the past (transsphenoidal resection in 2016 and 2019) with adjuvant radiotherapy, no chemotherapy was given. He also had diabetes mellitus type 1 (poorly controlled) and hypertension. He presented with bilateral lower limb weakness, anosmia, decreased oral intake, loss of taste for one week, and bilateral submandibular swelling that increased in size gradually over the past two years. There was no history of fever, cough, abdominal pain, or exposure to sick contacts. The patient reported past episodes of similar symptoms, but details are unclear. The patient’s family history is positive for diabetes mellitus type 1 in both parents. Lab tests in the emergency department showed hypokalemia and hyperglycemia as detailed in Table 1. He was admitted for further workup of the above complaints.

Test Patient Results Reference Range Unit Status
Hemoglobin 14.7 13-17 g/dL Normal
White blood cell (WBC) 17.9 4-10 10*9/L High
Neutrophils 15.89 2-7 10*9/L High
Lymphocytes 1.07 1-3 10*9/L Normal
Sodium 141 136-145 mmol/L Normal
Potassium 2.49 3.5-5.1 mmol/L Low (Panic)
Chloride 95 98-107 mmol/L Low
Glucose 6.52 4.11-5.89 mmol/L Elevated
C-reactive protein (CRP) 0.64 Less than 5 mg/L Normal
Erythrocyte sedimentation rate (ESR) 2 0-30 mm/h Normal
Creatinine 73 62-106 µmol/L Normal
Uric acid 197 202.3-416.5 µmol/L Normal
Alanine aminotransferase (ALT) 33.2 0-41 U/L Normal
Aspartate aminotransferase (AST) 18.6 0-40 U/L Normal
International Normalised Ratio (INR) 1.21 0.8-1.2 sec High
Prothrombin time (PT) 15.7 12.3-14.7 sec High
Lactate dehydrogenase (LDH) 491 135-225 U/L High
Thyroid-stimulating hormone (TSH) 0.222 0.27-4.20 mIU/L Low
Adrenocorticotropic hormone (ACTH) 106 ≤50 ng/L Elevated
Cortisol (after dexamethasone suppression) 1750 Morning hours (6-10 am): 172-497 nmol, Afternoon hours (4-8 pm): 74.1-286 nmol nmol/L Elevated (failure of suppression)
24-hour urine cortisol (after dexamethasone suppression) 5959.1 <120 nmol/24 hrs nmol/24hr Elevated (failure of suppression)
Table 1: Results of blood test at the time of hospitalization. Hypokalemia and high values of adrenocorticotropic hormone and cortisol were confirmed.

On examination, the patient’s vital signs were as follows: blood pressure was 154/77 mmHg, heart rate of 60 beats per minute, respiratory rate was 18 breaths per minute, oxygen saturation of 98% on room air, and a temperature of 36.7°C. The patient had a typical Cushingoid appearance with a moon face, buffalo hump, purple striae on the abdomen, central obesity, and hyperpigmentation of the skin. Submandibular lymph nodes were enlarged bilaterally. The examination of the submandibular lymph nodes showed a firm, fixed mass extending from the angle of the mandible to the submental space on the left side. Neurological examination showed weakness in both legs bilaterally (strength 3/5) and anosmia (checked by orthonasal smell test). The rest of the neurological exam was normal.

Laboratory findings revealed (in Table 1) a marked hypokalemia of 2.49 mmol/L and hyperglycemia of 6.52 mmol/L. The serum cortisol level was elevated at 1587 nmol/L. Serum ACTH levels were raised at 106 ng/L (normal value ≤50 ng/L). Moreover, the high-dose dexamethasone suppression test failed to lower the serum ACTH levels and serum and urine cortisol. Serum cortisol level after the suppression test was 1750 nmol/L, while 24-hour urine cortisol after the test was 5959.1 nmol/24hr. Serum ACTH levels after the test also remained high at 100mg/L. This indicated failure of ACTH suppression by high-dose dexamethasone, which points towards ectopic ACTH production. Other blood tests (complete blood count, liver function tests) were insignificant.

A computed tomography scan with contrast (CT scan) of the chest, abdomen, and pelvis, with a special focus on the adrenals, was negative for any malignancy or masses. CT scan of the neck showed bilaterally enlarged submandibular lymph nodes and an enlarged right lobe of the thyroid with nodules. Fine needle aspiration (FNA) of the thyroid nodules revealed a benign nature. Magnetic resonance imaging (MRI) of the brain showed a contrast-enhancing soft tissue lesion (18x18x10mm) in the midline olfactory groove area with extension into the frontal dura and superior sagittal sinus, suggesting recurrence of the previous ONB. There was evidence of previous surgery also. The pituitary gland was normal (Figures 1–2).

A-brain-MRI-(T1-weighted;-without-contrast;-sagittal-plane)-shows-a-soft-tissue-lesion-located-in-the-midline-olfactory-groove-area.-Dural-surface-with-extension-into-anterior-frontal-dura.
Figure 1: A brain MRI (T1-weighted; without contrast; sagittal plane) shows a soft tissue lesion located in the midline olfactory groove area. Dural surface with extension into anterior frontal dura.

MRI: Magnetic resonance imaging

A-brain-MRI-(T2-weighted;-without-contrast;-axial-plane)-shows-a-soft-tissue-lesion-located-in-the-midline-olfactory-groove-area.
Figure 2: A brain MRI (T2-weighted; without contrast; axial plane) shows a soft tissue lesion located in the midline olfactory groove area.

MRI: Magnetic resonance imaging

Octreotide scintigraphy showed three focal abnormal uptakes in the submandibular cervical nodes. Additionally, there was a moderate abnormal uptake at the midline olfactory groove with bilateral extension (Figure 3).

Whole-body-octreotide-scan-(15-mCi-99mTc-Octreotide-IV)-demonstrates-three-focal-abnormal-uptakes:-the-largest-(5.2-x-2.4-cm)-in-the-left-submandibular-region,-and-two-smaller-ones-on-the-right,-suggestive-of-lymph-node-uptake.-Additional-abnormal-uptake-was-seen-along-the-midline-of-the-olfactory-groove-region-with-bilateral-extension.-No-other-significant-abnormal-uptake-was-identified.
Figure 3: Whole-body octreotide scan (15 mCi 99mTc-Octreotide IV) demonstrates three focal abnormal uptakes: the largest (5.2 x 2.4 cm) in the left submandibular region, and two smaller ones on the right, suggestive of lymph node uptake. Additional abnormal uptake was seen along the midline of the olfactory groove region with bilateral extension. No other significant abnormal uptake was identified.

On microscopic examination, an excisional biopsy after the transcranial resection surgery of the frontal skull base tumor showed nests and lobules of round to oval cells with clear cytoplasm, separated by vascular and hyalinized fibrous stroma (Figures 4A–4B). Tumor cells show mild to moderate nuclear pleomorphism, and fine chromatin (Figure 4C). A fibrillary neural matrix is also present. Some mitotic figures can be seen. Immunohistochemical stains revealed positive staining for synaptophysin (Figure 4D) and chromogranin (Figure 4E). Stains for CK (AE1/AE3), CD45, Desmin, and Myogenin are negative. Immunostaining for ACTH was focally positive (Figure 4F), while the specimen of the cervical lymph nodes showed the same staining, indicating metastases. The cytomorphologic and immunophenotypic features observed are consistent with a Hyams grade II ONB, with ectopic ACTH production.

Histopathological-and-immunohistochemical-findings-of-olfactory-neuroblastoma.
Figure 4: Histopathological and immunohistochemical findings of olfactory neuroblastoma.

A (100x magnification) and B (200x magnification) – hematoxylin and eosin (H-E) staining shows cellular nests of round blue cells separated by hyalinized stroma. C (400x magnification) – nuclei show mild to moderate pleomorphism with fine chromatin. D (100x magnification) – an immunohistochemical stain for synaptophysin shows diffuse, strong cytoplasmic positivity within tumor cells. E (200x magnification) – tumor cells are positive for chromogranin. F (400x magnification) – ACTH cytoplasmic expression in tumor cells.

ACTH: adrenocorticotropic hormone

For his resistant hypokalemia, he had to be given intravenous (IV) and oral potassium chloride (KCL) repeatedly. The patient underwent transcranial resection of the frontal skull base tumor. The patient received cefazolin for seven days, and hydrocortisone for four days. After transcranial resection, his cortisol level decreased to 700 nmol/L. Furthermore, ACTH dropped, and serum potassium also normalized. Subsequently, the patient was transferred to the intensive care unit (ICU) for meticulous monitoring and continued care. In the ICU, the patient developed one episode of a generalized tonic-clonic seizure, which aborted spontaneously, and the patient received phenytoin and levetiracetam to prevent other episodes. A right-sided internal jugular vein and left transverse sinus thrombosis were also developed and treated with enoxaparin sodium. Following surgery, his low potassium levels improved, resulting in an improvement in his limb weakness. His other symptoms also gradually improved after surgery. Three weeks following the primary tumor resection, he underwent bilateral neck dissection with right hemithyroidectomy, for removal of the metastases. The patient opted out of chemotherapy and planned for an international transfer to his home country for further management. Other treatments that he received during hospitalization were ceftriaxone, azithromycin, and Augmentin®. Insulin was used to manage his diabetes, perindopril to regulate his blood pressure, and spironolactone to increase potassium retention. Omeprazole was administered to prevent GI bleeding and heartburn/gastroesophageal reflux disease relief after discharge.

Discussion

ONB was first described in 1924, and it is a rare neuroectodermal tumor that accounts for 2% of tumors affecting the nasal cavity [11]. Even though ONB has a good survival rate, long-term follow-up is necessary due to the disease’s high recurrence rate [2]. ONB recurrence has been approximated to range between 30% and 60% after successful treatment of the primary tumor [12]. Recurrent disease is usually locoregional and tends to have a long interval to relapse with a mean of six years [12]. The first reported case of ectopic ACTH syndrome caused by ONB was in 1987 by M Reznik et al., who reported a 48-year-old woman with ONB who developed a Cushing-like syndrome 28 months before her death [13].

The occurrence of Cushing’s syndrome due to ectopic ACTH can occur either in the initial tumor or even years later during its course or after recurrence [3,6,9,14]. Similar to the case of Abe et al. [3], our patient also presented with muscle weakness due to hypokalemia, which is a feature of Cushing’s syndrome. Hypokalemia is present at diagnosis in 64% to 86% of cases of EAS and is resistant to treatment [9,14], as seen in our case. In our patient, the exact time of development of Cushing’s syndrome could not be ascertained due to the non-availability of previous records. However, according to the patient, he started developing abdominal obesity, pigmentation, and buffalo hump in 2021 about two years after his second surgery for ONB.

The distinction between pituitary ACTH and ectopic ACTH involves utilizing CT/MRI of the pituitary, corticotropin-releasing hormone (CRH) stimulation test with petrosal sinus blood sampling, high dose dexamethasone suppression test, and checking serum K+ (more commonly low in ectopic ACTH) [2,15,16]. In our case, a CRH stimulation test was not available but CT/MRI brain, dexamethasone test, low serum potassium, plus the postoperative fall in cortisol levels, all pointed towards an ectopic ACTH source.

Conclusions

In conclusion, this case highlights the rare association between ONB and ectopic ACTH syndrome, which developed after tumor recurrence. The patient’s unique presentation of bilateral lower limb weakness and hypokalemia can cause diagnostic challenges, emphasizing the need for comprehensive diagnostic measures. Surgical intervention proved crucial, with postoperative cortisol values becoming normal, highlighting the efficacy of this approach. The occurrence of ectopic ACTH production in ONB patients, although very rare, is emphasized, so that healthcare professionals who deal with these tumors are aware of this complication. This report contributes valuable insights shedding light on the unique ONB manifestation causing ectopic ACTH syndrome. The ongoing monitoring of the patient’s clinical features will further enrich the understanding of the course of this uncommon phenomenon in the medical literature.

References

  1. Thompson LD: Olfactory neuroblastoma. Head Neck Pathol. 2009, 3:252-9. 10.1007/s12105-009-0125-2
  2. Abdelmeguid AS: Olfactory neuroblastoma. Curr Oncol Rep. 2018, 20:7. 10.1007/s11912-018-0661-6
  3. Abe H, Suwanai H, Kambara N, et al.: A rare case of ectopic adrenocorticotropic hormone syndrome with recurrent olfactory neuroblastoma. Intern Med. 2021, 60:105-9. 10.2169/internalmedicine.2897-19
  4. Yin Z, Wang Y, Wu Y, et al.: Age distribution and age-related outcomes of olfactory neuroblastoma: a population-based analysis. Cancer Manag Res. 2018, 10:1359-64. 10.2147/CMAR.S151945
  5. Platek ME, Merzianu M, Mashtare TL, Popat SR, Rigual NR, Warren GW, Singh AK: Improved survival following surgery and radiation therapy for olfactory neuroblastoma: analysis of the SEER database. Radiat Oncol. 2011, 6:41. 10.1186/1748-717X-6-41
  6. Elkon D, Hightower SI, Lim ML, Cantrell RW, Constable WC: Esthesioneuroblastoma. Cancer. 1979, 44:3-1087. 10.1002/1097-0142(197909)44:3<1087::aid-cncr2820440343>3.0.co;2-a
  7. Nieman LK, Biller BM, Findling JW, Newell-Price J, Savage MO, Stewart PM, Montori VM: The diagnosis of Cushing’s syndrome: an Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2008, 93:1526-40. 10.1210/jc.2008-0125
  8. Chabre O: Cushing syndrome: physiopathology, etiology and principles of therapy [Article in French]. Presse Med. 2014, 43:376-92. 10.1016/j.lpm.2014.02.001
  9. Isidori AM, Lenzi A: Ectopic ACTH syndrome. Arq Bras Endocrinol Metabol. 2007, 51:1217-25. 10.1590/s0004-27302007000800007
  10. Kunc M, Gabrych A, Czapiewski P, Sworczak K: Paraneoplastic syndromes in olfactory neuroblastoma. Contemp Oncol (Pozn). 2015, 19:6-16. 10.5114/wo.2015.46283
  11. Finlay JB, Abi Hachem R, Jang DW, Osazuwa-Peters N, Goldstein BJ: Deconstructing olfactory epithelium developmental pathways in olfactory neuroblastoma. Cancer Res Commun. 2023, 3:980-90. 10.1158/2767-9764.CRC-23-0013
  12. Ni G, Pinheiro-Neto CD, Iyoha E, et al.: Recurrent esthesioneuroblastoma: long-term outcomes of salvage therapy. Cancers (Basel). 2023, 15:1506. 10.3390/cancers15051506
  13. Reznik M, Melon J, Lambricht M, Kaschten B, Beckers A: Neuroendocrine tumor of the nasal cavity (esthesioneuroblastoma). Apropos of a case with paraneoplastic Cushing’s syndrome [Article in French]. Ann Pathol. 1987, 7:137-42.
  14. Kadoya M, Kurajoh M, Miyoshi A, et al.: Ectopic adrenocorticotropic hormone syndrome associated with olfactory neuroblastoma: acquirement of adrenocorticotropic hormone expression during disease course as shown by serial immunohistochemistry examinations. J Int Med Res. 2018, 46:4760-8. 10.1177/0300060517754026
  15. Clotman K, Twickler MTB, Dirinck E, et al.: An endocrine picture in disguise: a progressive olfactory neuroblastoma complicated with ectopic Cushing syndrome. AACE Clin Case Rep. 2017, 3:278-83. 10.4158/EP161729.CR
  16. Chung YS, Na M, Ku CR, Kim SH, Kim EH: Adrenocorticotropic hormone-secreting esthesioneuroblastoma with ectopic Cushing’s syndrome. Yonsei Med J. 2020, 61:257-61. 10.3349/ymj.2020.61.3.257

From https://www.cureus.com/articles/226080-olfactory-neuroblastoma-causing-cushings-syndrome-due-to-the-ectopic-adrenocorticotropic-hormone-acth-secretion-a-case-report?score_article=true#!/

Filed under: Cancer, Cushing's, pituitary, Rare Diseases, symptoms | Tagged: , , , , , | Leave a comment »

Cushing Syndrome due to a CRH- and ACTH-Secreting Silent Pheochromocytoma

Posted on February 26, 2024 by MaryO

Highlights

  • EAS should be considered in patients presenting with rapid progression of ACTH-dependent hypercortisolism causing severe clinical and metabolic abnormalities.
  • Ectopic ACTH secretion by a pheochromocytoma should be suspected in cases of ACTH-dependent Cushing syndrome in the presence of an adrenal mass.
  • If required, medical management with steroidogenesis inhibitors can be initiated at the time of EAS diagnosis to control clinical and metabolic derangements associated with severe hypercortisolemia
  • In patients with ACTH-dependent Cushing syndrome from an ectopic source, inhibiting steroidogenesis should be reserved for cases where the initial diagnosis is unclear or patients who are not suitable candidates for surgery.
  • Unilateral adrenalectomy is indicated in the management of ACTH/CRH-secreting pheochromocytomas and is typically curative.
  • Catecholamine blockade should be started prior to surgical removal of catecholamines-secreting pheochromocytomas.
  • A multidisciplinary approach is required to diagnose and manage this condition.

Abstract

Background/Objective

Ectopic co-secretion of corticotropin-releasing hormone (CRH) and adrenocorticotropic hormone (ACTH) in silent (i.e., noncatecholamine-secreting) pheochromocytoma is a rare cause of Cushing Syndrome (CS).

Case Report

A 57-year-old woman rapidly developed hypercortisolism, clinically manifesting as fatigue, muscle weakness, weight gain, and worsening hypertension, and biochemically characterized by hypokalemia and marked elevation of serum cortisol and plasma ACTH. This acute presentation suggested a diagnosis of ectopic ACTH syndrome (EAS). Imaging studies revealed a right adrenal mass that enhanced after administration of the radioisotope 68Ga-DOTATATE. Plasma metanephrines were normal in two separate measurements. The possibility of a silent pheochromocytoma was considered. After controlling her hypercortisolism with metyrapone and surgical preparation with alpha blockade, the patient underwent elective right adrenalectomy. Pathology revealed a pheochromocytoma that stained focally for ACTH and CRH. Postoperatively, cortisol levels normalized, the hypothalamic–pituitary–adrenal (HPA) axis was not suppressed, and clinical symptoms from hypercortisolism abated.

Discussion

Patients who exhibit a rapid progression of ACTH-dependent hypercortisolism should be screened for ectopic ACTH syndrome (EAS). The use of functional imaging radioisotopes (such as gallium DOTA-peptides), improves the detection of ACTH-secreting tumors. Preoperative treatment with steroidogenesis inhibitors helps control clinical and metabolic derangements associated with severe hypercortisolemia, while alpha blockade prevents the onset of an adrenergic crisis.

Conclusion

We present a rare case of EAS due to a silent pheochromocytoma that co-secreted ACTH and CRH. Pheochromocytoma should be considered in patients with EAS who have an adrenal mass even in the absence of excessive catecholamine secretion.

Key words

ectopic ACTH syndrome
Cushing Syndrome
non-catecholamine-secreting pheochromocytoma

Abbreviations

EAS

ectopic ACTH syndrome
CS

Cushing Syndrome
CRH

corticotropin-releasing hormone
ACTH

adrenocorticotropic hormone
DHEA-S

dehydroepiandrosterone sulfate
UFC

urine free cortisol
PRA

plasma renin activity

Introduction

Cushing Syndrome (CS) is rare, with an estimated incidence of 0.2-5.0 per million people per year, and prevalence of 39-79 per million (1). Ectopic ACTH Syndrome (EAS), a type of CS originating from extra-pituitary ACTH-secreting tumors, is uncommon. The prevalence of CS due to ACTH-secreting adrenal medullary lesions is not well established. However, EAS is observed in approximately 1.3% of all identified cases of pheochromocytoma (2). Recognizing EAS can be challenging due to its rarity, leading to delayed diagnosis.

Neuroendocrine neoplasms can produce CRH, which can lead to the secretion of ACTH by the pituitary. In certain cases, co-secretion of ACTH and CRH by an adrenal neoplasm has been observed. Only two published cases have provided definitive biochemical and immunohistochemical evidence of exclusive CRH secretion (3).

Case Report

A 57-year-old woman with a history of well-controlled hypertension sought care due to a two-month history of 60 lb weight gain, facial rounding, easy bruising, muscle weakness, lower extremity edema and acne. Her blood pressure control had worsened, and laboratory tests showed a markedly low serum potassium level of 1.8 mmol/L while taking hydrochlorothiazide. To manage her blood pressure, she was prescribed a calcium channel blocker, an angiotensin receptor blocker, and potassium supplements. However, her symptoms worsened, and she was referred to our emergency department. Blood pressure at presentation to our hospital was 176/86 mmHg. She had characteristic features of CS, including face rounding, supraclavicular fullness, dorsocervical fat accumulation, pedal edema, oral candidiasis, multiple forearm ecchymoses, and acneiform skin eruptions. No visible abdominal striae were present. She had no family history of pheochromocytoma, or multiple endocrine neoplasia type 2.

Serum cortisol level was 128 mcg/dL (normal range: 4.6-23.4) at 5 PM, with an ACTH level of 1055 pg/mL (normal range: 6-50); serum DHEA-S level was elevated at 445 mcg/dL (normal range: 8-188). Her 24-hour urine cortisol was at 12,566 mcg (normal range: 4.0-50.0). Plasma metanephrines were normal at <25 pg/mL (normal range: <57), and plasma normetanephrine was 44 (normal range: <148). A second plasma metanephrine measurement showed similar results. Serum aldosterone level and plasma renin activity were low at 2 ng/dL (normal range: 3-16) and 0.11 ng/mL/h (normal range: 0.25-5.82), respectively. Dopamine and methoxytyramine levels were not measured. An abdominal CT revealed a 4.8 x 4.5 x 5 cm right heterogeneously enhancing adrenal mass with a mean Hounsfield Unit of 68 in the non-contrast phase, and an absolute percentage washout of 30% (Fig 1A). The left adrenal gland appeared hyperplastic (Fig 1B). An Octreoscan, which was the in-hospital available nuclear medicine imaging modality, confirmed a 5.1 cm adrenal mass that was mild to moderately avid, with diffuse bilateral thickening of the adrenal glands and no other focal radiotracer avidity. A pituitary MRI did not show an adenoma, and EAS was suspected. Further evaluation with 68Ga-DOTATATE PET/CT (Fig 2) performed after her admission demonstrated an avid right adrenal mass consistent with a somatostatin receptor-positive lesion. No other suspicious tracer uptake was detected. These findings were consistent with a neuroendocrine tumor, such as pheochromocytoma.

  1. Download : Download high-res image (261KB)
  2. Download : Download full-size image

Fig. 1. Preoperative abdominal computed tomography scan showing a 4.8 x 4.5 x 5 cm right heterogeneously enhancing adrenal mass with irregular borders (A) and a hyperplastic left adrenal gland (B).

  1. Download : Download high-res image (219KB)
  2. Download : Download full-size image

Fig 2. 68Ga-DOTATATE PET/CT showing an avid right adrenal mass.

To control her symptoms while undergoing workup, the patient received oral metyrapone 500 mg thrice daily and oral ketoconazole 200 mg twice daily. Ketoconazole was stopped due to an increase in transaminases. The dosage of metyrapone was increased to 500 mg four times daily and later decreased to alternating doses of 250 mg and 500 mg four times daily. Within 3 weeks of starting medical therapy, serum cortisol level normalized at 20 mcg/dL. The 24-hour UFC improved to 246.3 mcg/24h. She experienced gradual improvement in facial fullness, acne, and blood pressure control.

The possibility of a silent pheochromocytoma was considered, and a-adrenergic blockade with doxazosin 1 mg daily was started 1 month prior surgery. She underwent surgery after two months of metyrapone therapy. With an unclear diagnosis and a large, heterogeneous adrenal mass, the surgical team elected to perform open adrenalectomy for en bloc resection due to concerns for an adrenal malignancy. The tumor was well-demarcated and did not invade surrounding structures (Figure 3A). H&E-stained sections showed classic morphologic features of a pheochromocytoma (Figure 3B), with immunohistochemistry demonstrating strong immunoreactivity for synaptophysin and chromogranin, and negative SF- I and inhibin stains excluding an adrenal cortical lesion. The sections analyzed by QuPath (4) revealed that approximately 4% of ce11s were ACTH cells, often found in isolation, and had a clear, high signal-to-noise staining (Figure 3C). CRH cells were less prevalent, comprising about 2.4% of the total analyzed cells, and tended to cluster together (Figure 3D). These cells had more background staining, resulting in a lower signal- to-noise ratio.

  1. Download : Download high-res image (663KB)
  2. Download : Download full-size image

Figure 3. Gross and Histopathological analysis of the patient’s pheochromocytoma. (A) Image of the gross excised specimen. (B) H&E staining (200x final magnification) demonstrates prominent vascularity and cells with finely granular, eosinophilic cytoplasm and salt-and-pepper chromatin. (C) ACTH staining (200x final magnification) shows clear and isolated positive cells, representing about 4.0% of the section analyzed by QuPath. (D) CRH staining (200x final magnification) reveals tight clusters of positive cells, accounting for 2.4% of the total cells. Positive (human placenta and hypothalamus) and negative (thyroid gland) control tissues performed as expected (data not shown).

The patient’s postoperative recovery was uneventful, with a short course of hydrocortisone which was stopped 1 week after surgery after HPA axis evaluation showed normal results. After one month, hypercortisolism had resolved, as shown by a normal 24-hour UFC at 28 mcg.

Administration of dexamethasone at 11 PM resulted in suppression of morning cortisol to 0.8 and 0.6 mcg/dL 1 and 7 months after surgery, respectively. Her liver function tests normalized, and blood pressure was well-controlled with amlodipine 10 mg daily and losartan 100 mg daily. Genetic testing for pheochromocytoma predisposition syndromes is currently planned.

Discussion

EAS accounts for 10-20% of cases of ACTH-dependent CS (5). This condition can be caused by several neuroendocrine neoplasms that produce bioactive ACTH (6) In the literature, we have found 99 documented cases of EAS caused by a pheochromocytoma. Of these, 93% showed ACTH expression. Only two cases have been reported with dual staining of ACTH and CRH (7). Exclusive CRH production has only been reported in two cases (8:9). However, the true prevalence of CRH-producing pheochromocytomas might be underestimated, as most cases testing for CRH expression was not performed.

Although the clinical presentation of EAS may be highly variable, there is often a rapid onset of hypercortisolism accompanied by severe catabolic symptoms. The diagnostic process should focus on identifying the location of a potential neuroendocrine neoplasm responsible for the ACTH secretion. Sometimes the peripheral origin of ACTH must be confirmed by inferior petrosal sinus sampling (IPSS). In this case, given the clinical presentation consistent with EAS, negative pituitary MRI, and the presence of an adrenal mass that needed to be removed independently, IPSS was not performed.

Neuroendocrine neoplasms express somatostatin receptors on their surface, which allow functional imaging using [11 lln]-pentetreotide (Octreoscan). However, Octreoscan has a low sensitivity in detecting occult EAS. In cases where the tumor is in the abdomen and pelvis, Octreoscan has limited utility in locating the source of ACTH (10). This increased risk of false negatives is caused by physiological tracer uptake by the liver, spleen, urinary tract, bowel, and gallbladder. The use of Gallium-68 labeled somatostatin receptor ligands (PET/CT 68Ga-DOTATATE) is more effective in detecting somatostatin receptors (SSTR2) than [11lln]-pentetreotide due to its higher spatial resolution and affinity (11)_ This test was performed after discharge form the hospital to rule out the presence of a second, smaller neuroendocrine tumor that the Octreoscan might have missed. A new molecular imaging technique targeting CRH receptors (68Ga CRH PET/CT) has shown potential in identifying tumors expressing CRH, but its availability remains limited (12). In our patient’s case, both the Octreoscan and 68Ga- DOTATATE successfully identified the adrenal tumor as a potential ACTH/CRH secretion source.

According to relevant guidelines, presurgical adrenergic blockade is recommended for patients with biochemical evidence of catecholamine excess (13, 14). Conversely, silent pheochromocytomas can generally be operated without alpha blockade (15). Despite this, we opted to administer pre-operative alpha blockade as a precautionary measure for this patient.

Pathology examination confirmed the diagnosis of pheochromocytoma. ACTH and CRH staining demonstrated that clear and significant populations of two separate ACTH and CRH positive cells were present in the excised pheochromocytoma. ACTH/CRH cells were dispersed throughout various regions of the pheochromocytoma rather than being well-defined, separate histological entities. As a result, there is no indication that this resulted from collision tumors, but rather random mutation and expansion of tumor cells into ACTH or CRH secreting cells. These results have limitations, including variation in ACTH and CRH expressing regions due to tumor heterogeneity, nonspecific binding of polyclonal antibodies, and normal low-rate false negative/positive detection using QuPath.

Post-surgical normal HPA activity was likely due to the de-suppression of the HPA axis by medical therapy, but it may also be explained by chronic stimulation of corticotroph cells induced by ectopic CRH secretion.

The standard approach to managing EAS involves surgical intervention. However, surgery may not be a viable option in cases where the source of ACTH production is unknown. Medical therapy to reduce or block excess cortisol can be used in such circumstances.

Conclusions

In conclusion, a pheochromocytoma causing EAS should be considered even in the absence of elevated plasma metanephrines. These tumors may simultaneously express ACTH and CRH.CRH.

References

Cited by (0)

Sources of support: None

Permission in the form of written consent from patient for use of actual test results was obtained.

Cushing in silent pheochromocytoma

Clinical Relevance

This case highlights the importance of considering ectopic ACTH secretion by a pheochromocytoma in patients presenting with rapid progression and considerable clinical hypercortisolism concomitant with an adrenal mass and elevated plasma ACTH. This represents an unusual manifestation of a specific subtype of ACTH/CRH-secreting pheochromocytoma that did not exhibit catecholamine secretion

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper

∗

These 2 authors contributed equally to this work

From https://www.sciencedirect.com/science/article/pii/S2376060524000075

Filed under: adrenal, Cushing's, Rare Diseases | Tagged: , , , | Leave a comment »

« Previous Page — Next Page »