Delayed Diagnosis of Ectopic Cushing Syndrome

Abstract

Here, we present the case of a 40-year-old man in whom the diagnosis of ectopic adrenocorticotropin (ACTH) syndrome went unrecognized despite evaluation by multiple providers until it was ultimately suspected by a nephrologist evaluating the patient for edema and weight gain. On urgent referral to endocrinology, screening for hypercortisolism was positive by both low-dose overnight dexamethasone suppression testing and 24-hour urinary free cortisol measurement. Plasma ACTH values confirmed ACTH-dependent Cushing syndrome. High-dose dexamethasone suppression testing was suggestive of ectopic ACTH syndrome. Inferior petrosal sinus sampling demonstrated no central-to-peripheral gradient, and 68Ga-DOTATATE scanning revealed an avid 1.2-cm left lung lesion. The suspected source of ectopic ACTH was resected and confirmed by histopathology, resulting in surgical cure. While many patients with Cushing syndrome have a delayed diagnosis, this case highlights the critical need to increase awareness of the signs and symptoms of hypercortisolism and to improve the understanding of appropriate screening tests among nonendocrine providers.

Introduction

Even in the face of overt clinical signs and symptoms of hypercortisolism, diagnosing Cushing syndrome requires a high index of suspicion, and people with hypercortisolism experience a long road to diagnosis. In a recent meta-analysis including more than 5000 patients with Cushing syndrome, the mean time to diagnosis in all Cushing syndrome, including Cushing disease and ectopic adrenocorticotropin (ACTH) syndrome, was 34 months (1). Reasons for delayed diagnosis are multifactorial, including the nonspecific nature of subjective symptoms and objective clinical signs, as well as notorious challenges in the interpretation of diagnostic testing. Furthermore, the health care system’s increasingly organ-specific referral patterns obfuscate multisystem disorders. Improving the recognition of and decreasing time to diagnosis in Cushing syndrome are critical factors in reducing morbidity and mortality.

Here, we present the case of a patient who, despite classic signs of Cushing syndrome as well as progressive physical and mental decline, remained undiagnosed for more than 3 years while undergoing repeated evaluation by primary care and subspecialty providers. The case (1) highlights the lack of awareness of Cushing syndrome as a potential unifying diagnosis for multiorgan system problems; (2) underscores the necessity of continued education on the signs and symptoms of hypercortisolism, appropriate screening for hypercortisolism, and early referral to endocrinology; and (3) provides an opportunity for systemic change in clinical laboratory practice that could help improve recognition of pathologic hypercortisolism.

Case Presentation

In August 2018, a previously healthy 40-year-old man with ongoing tobacco use established care with a primary care provider complaining that he had been ill since the birth of his son 13 months prior. He described insomnia, headaches, submandibular swelling, soreness in his axillary and inguinal regions, and right-sided chest discomfort (Fig. 1). Previously, he had been diagnosed with sinusitis, tonsillitis, and allergies, which had been treated with a combination of antibiotics, antihistamines, and intranasal glucocorticoids. He was referred to otolaryngology where, in the absence of cervical lymphadenopathy, he was diagnosed with sternocleidomastoid pain with recommendations to manage conservatively with stretching and massage. A chest x-ray demonstrated a left apical lung nodule. Symptoms continued unabated throughout 2019, now with a cough. Repeat chest x-ray demonstrated opacities lateral to the left hilum that were attributed to vascular structures.

 

Figure 1.

Timeline of development of subjective symptoms and objective clinical findings preceding diagnosis and surgical cure of ectopic Cushing syndrome.

In May 2020, increasingly frustrated with escalating symptoms, the patient transitioned care to a second primary care provider and was diagnosed with hypertension. He complained of chronic daily headaches that prompted brain imaging with magnetic resonance imaging (MRI), which noted findings consistent with left maxillary silent sinus syndrome. He was sent back to otolaryngology, which elected to proceed with sinus surgery. During this time, he suffered a fibular fracture for which he was evaluated by orthopedic surgery. In the second half of 2020, he was seen by neurology to evaluate his chronic headaches and paresthesias with electromyography demonstrating a left ulnar mononeuropathy consistent with cubital tunnel syndrome. His primary care provider diagnosed him with fibromyalgia for which he started physical therapy, and he was referred to a pain clinic for cognitive behavioral therapy. Unfortunately his wife, dealing with her husband’s increasing cognitive and personality changes including irritability and aggression, filed for divorce.

At the end of 2020, the patient developed bilateral lower extremity edema and was prescribed hydrochlorothiazide, subsequently developing hypokalemia attributed to diuretic use. With worsening bilateral lower extremity edema and new dyspnea on exertion, he was evaluated for heart failure with an echocardiogram, which was unremarkable. Over the next several months, he gained approximately 35 pounds (∼16 kg). It was in the setting of weight gain that he was first evaluated for hypercortisolism with random serum cortisol of 22.8 mcg/dL (629 nmol/L) and 45.6 mcg/dL (1258 nmol/L) in the late morning and mid-day, respectively. No reference range was provided for the times of day at which these laboratory values were drawn. Although these serum cortisol values were above provided reference ranges for other times of day, they were not flagged as abnormal by in-house laboratory convention, and they were overlooked. The search for other etiologies of his symptoms continued.

In early 2021, diuretic therapy and potassium supplementation were escalated for anasarca. He developed lower extremity cellulitis and received multiple courses of antibiotics. Skin biopsy performed by dermatology demonstrated disseminated Mycobacterium and later Serratia (2), prompting referral to infectious disease for management. Additional subspecialty referrals included rheumatology (polyarthralgia) and gastroenterology (mildly elevated alanine transaminase with planned liver biopsy). In July 2021, he was evaluated for edema by nephrology, where the constellation of subjective symptoms and objective data including hypertension, central weight gain, abdominal striae, fracture, edema, easy bruising, medication-induced hypokalemia, atypical infections, and high afternoon serum cortisol were noted, and the diagnosis of Cushing syndrome was strongly suspected. Emergent referral to endocrinology was placed.

Diagnostic Assessment

At his first clinic visit with endocrinology in June 2021, the patient’s blood pressure was well-controlled on benazepril. Following weight gain of 61 pounds (∼28 kg) in the preceding 2 years, body mass index was 33. Physical examination demonstrated an ill-appearing gentleman with dramatic changes when compared to prior pictures (Fig. 2), including moon facies, dorsocervical fat pad, violaceous abdominal striae, weeping lower extremity skin infections, an inability to stand without assistance from upper extremities, and depressed mood with tangential thought processes.

 

Figure 2.

Photographic representation of physical changes during the years leading up to diagnosis of ectopic Cushing syndrome in June 2021 and after surgical resection of culprit lesion.

Diagnostic workup for hypercortisolism included a morning cortisol of 33.4 mcg/dL (922 nmol/L) (normal reference range, 4.5-22.7 mcg/dL) and ACTH of 156 pg/mL (34 pmol/L) (normal reference range, 7.2-63 pg/mL) following bedtime administration of 1-mg dexamethasone, and 24-hour urine free cortisol of 267 mcg/24 hours (737 nmol/24 hours) (normal reference range, 3.5-45 mcg/24 hours). Morning serum cortisol and plasma ACTH following bedtime administration of 8-mg dexamethasone were 27.9 mcg/dL (770 nmol/L) and 98 pg/mL (22 pmol/L), respectively. Given concern for potential decompensation, he was hospitalized for expedited work-up. Brain MRI did not demonstrate a pituitary lesion (Fig. 3), and inferior petrosal sinus sampling under desmopressin stimulation showed no central-to-peripheral gradient (Table 1). He underwent a positron emission tomography–computed tomography 68Ga-DOTATATE scan that demonstrated a 1.2-cm left pulmonary nodule with radiotracer uptake (Fig. 4).

 

Figure 3.

A, Precontrast and B, postcontrast T1-weighted sagittal magnetic resonance imaging of the sella. Images were affected by significant motion degradation, precluding clear visualization of the pituitary gland on coronal imaging.

 

Figure 4.

68Ga-DOTATATE imaging. A, Coronal and B, axial views of the chest after administration of radiopharmaceutical. Arrow in both panels indicates DOTATATE-avid 1.2-cm left lung lesion.

 

Table 1.

Bilateral petrosal sinus and peripheral adrenocorticotropin levels preintravenous and postintravenous injection of desmopressin acetate 10 mcg

Time post DDAVP, min Left petrosal ACTH Left petrosal:peripheral ACTH Right petrosal ACTH Right petrosal:peripheral ACTH Peripheral ACTH Left:right petrosal ACTH
0 172 pg/mL
(37.9 pmol/L)
1.1 173 pg/mL
(38.1 pmol/L)
1.2 150 pg/mL
(33.0 pmol/L)
1.0
3 288 pg/mL
(63.4 pmol/L)
1.8 292 pg/mL
(64.3 pmol/L)
1.8 162 pg/mL
(35.7 pmol/L)
1.0
5 348 pg/mL
(76.6 pmol/L)
1.8 341 pg/mL
(75.1 pmol/L)
1.8 191 pg/mL
(42.1 pmol/L)
1.0
10 367 pg/mL
(80.8 pmol/L)
1.3 375 pg/mL
(82.6 pmol/L)
1.3 278 pg/mL
(61.2 pmol/L)
1.0

Abbreviations: ACTH, adrenocorticotropin; DDAVP, desmopressin acetate.

Treatment

The patient was started on ketoconazole 200 mg daily for medical management of ectopic ACTH-induced hypercortisolism while awaiting definitive surgical treatment. Within a month of initial endocrinology evaluation, he underwent thoracoscopic left upper lobe wedge resection with intraoperative frozen histopathology section consistent with a well-differentiated neuroendocrine tumor and final pathology consistent with a well-differentiated neuroendocrine tumor. Staining for ACTH was positive (Fig. 5). Postoperative day 1 morning cortisol was 1.4 mcg/dL (39 nmol/L) (normal reference range, 4.5-22.7 mcg/dL). He was started on glucocorticoid replacement with hydrocortisone and was discharged from his surgical admission on hydrocortisone 40 mg in the morning and 20 mg in the afternoon.

 

Figure 5.

Lung tumor histopathology. A, The tumor was epicentered around a large airway (asterisk) and showed usual architecture for carcinoid tumor. B, The tumor cells had monomorphic nuclei with a neuroendocrine chromatin pattern, variably granulated cytoplasm, and a delicate background vascular network. By immunohistochemistry, the tumor cells were strongly positive for C, synaptophysin; D, CAM5.2; and E, adrenocorticotropin. F, Ki-67 proliferative index was extremely low (<1%).

Outcome and Follow-up

Approximately 12 days after discharge, the patient was briefly readmitted from the skilled nursing facility where he was receiving rehabilitation due to a syncopal event attributed to hypovolemia. This was felt to be secondary to poor oral intake in the setting of both antihypertensive and diuretic medications as well as an episode of emesis earlier in the morning precluding absorption of his morning hydrocortisone dose. Shortly after this overnight admission, he was discharged from his skilled nursing facility to home. In the first month after surgery, he lost approximately 30 pounds (∼14 kg) and had improvements in sleep and mood.

Eight months after surgery, hydrocortisone was weaned to 10 mg daily. Cosyntropin stimulation testing holding the morning dose showed 1 hour cortisol 21.5 mcg/dL (593 nmol/L). Hydrocortisone was subsequently discontinued. In June 2022, 1 year following surgery, 3 sequential midnight salivary cortisol tests were undetectable. At his last visit with endocrinology in June 2023, he felt well apart from ongoing neuropathic pain in his feet and continued but improved mood disturbance. Though his health has improved dramatically, he continues to attribute his divorce and substantial life disruption to his undiagnosed hypercortisolism.

Discussion

Endogenous neoplastic hypercortisolism encompasses a clinical spectrum from subclinical disease, as is common in benign adrenal cortical adenomas, to overt Cushing syndrome of adrenal, pituitary, and ectopic origin presenting with dramatic clinical manifestations (3) and long-term implications for morbidity and mortality (4). Even in severe cases, a substantial delay in diagnosis is common. In this case, despite marked hypercortisolism secondary to ectopic ACTH syndrome, the patient’s time from first symptoms to diagnosis was more than 3 years, far in excess of the typical time to diagnosis in this subtype, noted to be 14 months in 1 study (1).

He initially described a constellation of somatic symptoms including subjective neck swelling, axillary and inguinal soreness, chest discomfort, and paresthesias, and during the year preceding diagnosis, he developed hypertension, fibular fracture, mood changes, weight gain, peripheral edema, hypokalemia, unusual infections, and abdominal striae. Each of these symptoms in isolation is a common presentation in the primary care setting, therefore the challenge arises in distinguishing common, singular causes from rare, unifying etiologies, especially given the present epidemics of diabetes, obesity, and associated cardiometabolic abnormalities. By Endocrine Society guidelines, the best discriminatory features of Cushing syndrome in the adult population are facial plethora, proximal muscle weakness, abdominal striae, and easy bruising (5). Furthermore, Endocrine Society guidelines suggest evaluating for Cushing disease when consistent clinical features are present at a younger-than-expected age or when these features accumulate and progress, as was the case with our patient (5).

However, even when the diagnosis is considered, the complexities of the hypothalamic-pituitary-adrenal axis make selection and interpretation of screening tests challenging outside the endocrinology clinic. We suspect that in most such situations, a random serum cortisol measurement is far more likely to be ordered than a validated screening test, such as dexamethasone suppression testing, urine free cortisol, and late-night salivary cortisol per Endocrine Society guidelines (5). Although random serum cortisol values are not considered a screening test for Cushing syndrome, elevated values can provide a clue to the diagnosis in the right clinical setting. In this case, 2 mid-day serum cortisols were, by in-house laboratory convention, not flagged as abnormal despite the fact that they were above the upper limit of provided reference ranges. We suspect that the lack of electronic medical record flagging of serum cortisol values contributed to these values being incorrectly interpreted as ruling out the diagnosis.

Cushing syndrome remains among the most evasive and difficult diagnoses in medicine due to the doubly difficult task of considering the disorder in the face of often protean signs and symptoms and subsequently conducting and interpreting screening tests. The challenges this presents for the nonendocrinologist have recently been recognized by a group in the United Kingdom after a similarly overlooked case (6). We believe that our case serves as a vivid illustration of the diagnostic hurdles the clinician faces and as a cautionary tale with regard to the potential downstream effects of a delay in diagnosis. Standardization of clinical laboratory practices in flagging abnormal cortisol values is one such intervention that may aid the busy clinician in more efficiently recognizing laboratory results suggestive of this diagnosis. While false-positive case detection is a significant downside to this approach, given the potential harm in delayed or missed diagnosis, the potential benefits may outweigh the risks.

Learning Points

  • People with Cushing syndrome frequently experience a prolonged time to diagnosis, in part due to lack of recognition in the primary care and nonendocrine subspecialty settings of the constellation of clinical findings consistent with hypercortisolism.
  • Endocrine Society guidelines recommend against random serum cortisol as initial testing for Cushing syndrome in favor of dexamethasone suppression testing, urine free cortisol, and late-night salivary cortisol.
  • Increased awareness of Cushing syndrome by primary care providers and specialists in other fields could be an important and impactful mechanism to shorten the duration of symptom duration in the absence of diagnosis and hasten cure where cure is achievable.
  • We suggest clinical laboratories consider standardizing flagging abnormal cortisol values to draw attention to ordering providers and perhaps lower the threshold for endocrinology referral if there is any uncertainty in interpretation, especially in the context of patients with persistent symptoms and elusive diagnoses.

Acknowledgments

We are grateful to the patient for allowing us to present his difficult case to the community with the hopes of improving time to diagnosis for patients with hypercortisolism.

Contributors

All authors made individual contributions to authorship. J.M.E., E.M.Z., and K.R.K. were involved in the diagnosis and management of this patient. B.C.M., J.M.E., E.M.Z., and K.R.K. were involved in manuscript submission. S.M.J. performed and analyzed histopathology and prepared the figure for submission. All authors reviewed and approved the final draft.

Funding

No public or commercial funding.

Disclosures

J.M.E. was on the editorial board of JCEM Case Reports at the time of initial submission.

Informed Patient Consent for Publication

Signed informed consent obtained directly from the patient.

Data Availability Statement

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

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Abbreviations

 

  • ACTH

    adrenocorticotropin

  • MRI

    magnetic resonance imaging

© The Author(s) 2024. Published by Oxford University Press on behalf of the Endocrine Society.
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Clinical Features and Treatment Options for Pediatric Adrenal Incidentalomas

Abstract

Background

The aim of this study was to investigate the clinical features and treatment options for pediatric adrenal incidentalomas(AIs) to guide the diagnosis and treatment of these tumors.

Methods

The clinical data of AI patients admitted to our hospital between December 2016 and December 2022 were collected and retrospectively analyzed. All patients were divided into neonatal and nonneonatal groups according to their age at the time of the initial consultation.

Results

In the neonatal group, 13 patients were observed and followed up, and the masses completely disappeared in 8 patients and were significantly reduced in size in 5 patients compared with the previous findings. Four patients ultimately underwent surgery, and the postoperative pathological diagnosis was neuroblastoma in three patients and teratoma in one patient. In the nonneonatal group, there were 18 cases of benign tumors, including 9 cases of ganglioneuroma, 2 cases of adrenocortical adenoma, 2 cases of adrenal cyst, 2 cases of teratoma, 1 case of pheochromocytoma, 1 case of nerve sheath tumor, and 1 case of adrenal hemorrhage; and 20 cases of malignant tumors, including 10 cases of neuroblastoma, 9 cases of ganglioneuroblastoma, and 1 case of adrenocortical carcinoma.

Conclusions

Neuroblastoma is the most common type of nonneonatal AI, and detailed laboratory investigations and imaging studies are recommended for aggressive evaluation and treatment in this population. The rate of spontaneous regression of AI is high in neonates, and close observation is feasible if the tumor is small, confined to the adrenal gland and has no distant metastasis.

Peer Review reports

Background

The incidence of adrenal incidentaloma (AI) is increasing due to the increased frequency of imaging and improved imaging sensitivity [1]. AI is relatively common in adults, and several organizations, such as the American Association of Clinical Endocrinologists/American Association of Endocrine Surgeons and the European Society Endocrinology, have proposed specific protocols to guide the evaluation, treatment, and follow-up management of AI in adults [2]. Although AI, a nonfunctioning adrenocortical adenoma, is most common in adults, neuroblastoma is the most common incidental tumor of the adrenal gland in children. In addition, in the neonatal period, which is a more complex stage of childhood, the biology of adrenal masses found in this age group is also more specific, and the nature of these masses can range from spontaneous regression to rapid progression to aggressive disease with metastatic dissemination and even death. Given that AI is the most common malignant tumor, the management of AI in children cannot be simply based on the measurements used in adult AI. In this study, we retrospectively analyzed the clinical data of pediatric AI patients in a single center to investigate the clinical characteristics and management of AI in children.

Methods

A total of 66 children with adrenal tumors were diagnosed and treated at the Department of Urology of the Children’s Hospital of Nanjing Medical University from December 2016 to December 2022. A total of 55 cases were detected during physical examination, or the patients were diagnosed and received treatment for diseases other than adrenal disease after excluding adrenal tumors detected due to typical clinical manifestations or signs such as centripetal obesity and precocious puberty. Research protocols involving human materials were approved by the Medical Ethics Committee of the Children’s Hospital of Nanjing Medical University. All clinical information, radiological diagnosis, laboratory test results, intervention results, and follow-up data were collected from the department’s database.

All the children underwent ultrasonography and CT scanning, and 11 children underwent MRI. In addition to routine tests such as blood routine and biochemical indexes, the examination and evaluation of adrenal endocrine hormones and tumor markers included (1) plasma cortisol and ACTH levels, (2) plasma catecholamine and metabolite determination, (3) plasma renin and plasma aldosterone, (4) urinary vanillylmandelic acid/homovanillic acid(VMA/HVA), and (5) AFP, CEA, NSE, and CA19-9. Five patients underwent a low-dose dexamethasone suppression test. Seventeen of the 55 patients were treated with watch-waiting therapy, 4 of the 17 ultimately underwent surgery, 4 of the 38 patients underwent tumor biopsy, and 34 underwent adrenalectomy.

The data were analyzed using Graph Pad Prism 8. The measurement data are expressed as ‾x ± sd. The maximum diameter of the tumors, age of the patients with benign and malignant tumors, and maximum diameter of the tumors between the laparoscopic surgery group and the open surgery group were compared using paired t tests, and the percentages of the count data were compared using Fisher’s exact test.

Results

In this study, all patients were divided into two groups according to their age at the time of consultation: the neonate group and the nonneonate group.

Neonate group:

There were 7 male and 10 female patients, 7 of whom were diagnosed via prenatal examination and 10 of whom were diagnosed after birth. Five patients were diagnosed with lesions on the left side, 12 patients were diagnosed with lesions on the right side, and the maximal diameters of the masses ranged from 16 to 48 mm. The characteristics of the AIs in the neonate group are presented in Table 1.

Table 1 Characteristics of AI in the neonates group

Among the 17 patients, 8 had cystic masses with a maximum diameter of 1648 mm, 5 had cystic-solid masses with a maximum diameter of 3339 mm, and 4 had solid masses with a maximum diameter of 1845 mm. Two patients with solid adrenal gland masses suggested by CT scan had obvious elevations in serum NSE and maximum diameters of 44 and 45 mm, respectively. These patients underwent adrenal tumor resection, and the pathology diagnosed that they had neuroblastomas(NB). In one patient, the right adrenal gland was 26 × 24 × 27 mm in size with slightly elevated echogenicity at 38 weeks after delivery, and the mass increased to a size of 40 × 39 × 29 mm according to the 1-month postnatal review. MRI suggested that the adrenal gland tumor was associated with liver metastasis, and the pathology of the tumor suggested that it was NB associated with liver metastasis after surgical resection (stage 4 S, FH). One child was found to have 25 × 24 × 14 mm cystic echoes in the left adrenal region during an obstetric examination, and ultrasound revealed 18 × 11 mm cystic solid echoes 5 days after birth. Ultrasound revealed 24 × 15 mm cystic solid echoes at 2 months. Serum NSE and urinary VMA were normal, and the tumor was excised due to the request of the parents. Pathology suggested a teratoma in the postoperative period. A total of 13 children did not receive surgical treatment or regular review via ultrasound, serum NSE or urine VMA. The follow-up time ranged from 1 to 31 months, with a mean of 9.04 ± 7.61 months. Eight patients had complete swelling, and 5 patients were significantly younger than the previous patients. Nonneonate group:

There were 24 male and 14 female patients in the nonneonate group; 24 patients had lesions on the left side, 14 patients had lesions on the right side, and the maximal diameters of the masses ranged from 17 to 131 mm. Most of these tumors were found during routine physical examinations or incidentally during examinations performed for various complaints, such as gastrointestinal symptoms, respiratory symptoms, or other related conditions. As shown in Table 2, abdominal pain was the most common risk factor (44.7%) for clinical onset, followed by routine physical examination and examination for respiratory symptoms.

Table 2 Clinical presentations leading to discovery of AI in non-neonate group

Among the 38 patients, 10 had NBs with maximum diameters ranging from 20 to 131 mm, 9 had ganglion cell neuroblastomas with maximum diameters ranging from 33.6 to 92 mm, 9 had ganglion cell neuromas with maximum diameters ranging from 33 to 62 mm, 2 had adrenal adenomas with maximum diameters ranging from 17 to 70 mm, 1 had a cortical carcinoma with a maximum diameter of 72 mm, 2 had adrenal cysts with maximum diameters ranging from 26 to 29 mm, 2 had mature teratomas with maximum diameters of 34 and 40 mm, 1 had a pheochromocytoma with a diameter of 29 mm, 1 had a nerve sheath tumor with a diameter of 29 mm, and 1 patient with postoperative pathological confirmation of partial hemorrhagic necrosis of the adrenal gland had focal calcification with a maximum diameter of 25 mm (Table 3).

Table 3 Distribution of different pathologies among AI with various sizes in non-neonate group

The mean age of children with malignant tumors was significantly lower than that of children with benign tumors (57.95 ± 37.20 months vs. 105.0 ± 23.85 months; t = 4.582, P < 0.0001). The maximum diameter of malignant tumors ranged from 20 to 131 mm, while that of benign tumors ranged from 17 to 72 mm, and the maximum diameter of malignant tumors was significantly greater than that of benign tumors (65.15 ± 27.61 mm v 37.59 ± 12.98 mm; t = 3.863, P = 0.0004). Four biopsies, 5 laparoscopic adrenal tumor resections and 11 open adrenal tumor resections were performed for malignant tumors, and 16 laparoscopic adrenal tumor resections and 2 open procedures were performed for benign tumors. The maximum diameter of the tumors ranged from 17 to 62 mm in 21 children who underwent laparoscopic surgery and from 34 to 99 mm in 13 children who underwent open resection; there was a statistically significant difference in the maximum diameter of the tumors between the laparoscopic surgery group and the open surgery group (35.63 ± 10.36 mm v 66.42 ± 20.60 mm; t = 5.798, P < 0.0001).

Of the 42 children with definitive pathologic diagnoses at surgery, 23 had malignant tumors, and 19 had benign tumors. There were 15 malignant tumors with calcification on imaging and 5 benign tumors. The percentage of malignant tumors with calcifications in was significantly greater than that of benign tumors (65.22% v 26.32%; P = 0.0157). In the present study, all the children underwent CT, and 31 patients had postoperative pathological confirmation of NB. A total of 26 patients were considered to have neurogenic tumors according to preoperative CT, for a diagnostic compliance rate of 83.97%. Three children were considered to have cortical adenomas by preoperative CT, and 1 was ultimately diagnosed by postoperative pathology, for a diagnostic compliance rate of 33.33%. For 4 patients with teratomas and adrenal cysts, the CT findings were consistent with the postoperative pathology. According to our research, NB 9-110HU, GNB 15-39HU, GB 19-38HU, ACA 8HU, adrenal cyst 8HU, and cellular achwannoma 17HU.

Discussion

According to the clinical practice guidelines developed by the European Society of Endocrinology and European Network for the Study of Adrenal Tumors, AI is an adrenal mass incidentally detected on imaging not performed for a suspected adrenal disease [3]. The prevalence of AI is approximately 4%, and the incidence increases with age [4]. Most adult AIs are nonfunctioning benign adrenal adenomas (up to 75%), while others include functioning adrenal adenomas, pheochromocytomas, and adrenocortical carcinomas [5]. In contrast to the disease spectrum of adult AI cases, NB is the most common tumor type among children with AI, and benign cortical adenomas, which account for the vast majority of adult AI, accounting for less than 0.5% of cases in children [6]. According to several guidelines, urgent assessment of an AI is recommended in children because of a greater likelihood of malignancy [37].

When an adult patient is initially diagnosed with AI, it should be clear whether the lesion is malignant and functional. In several studies, the use of noncontrast CT has been recommended as the initial imaging method for adrenal incidentaloma; a CT attenuation value ≤ 10 HU is used as the diagnostic criterion for benign adenomas; and these methods have a specificity of 71-79% and a sensitivity of 96-98% [89]. A CT scan of tumors with diameters greater than 4 to 6 cm, irregular margins or heterogeneity, a CT attenuation value greater than 10 HU, or a relative contrast enhancement washout of less than 40% 10 or 15 min after administration of contrast media on enhanced CT is considered to indicate potential malignancy [7]. As the most common AI in children, NB often appears as a soft tissue mass with uneven density on CT, often accompanied by high-density calcified shadows, low-density cystic lesions or necrotic areas. CT scans can easily identify more typical NBs, and for those AIs that do not show typical calcified shadows on CT, it is sometimes difficult to differentiate neurogenic tumors from adenomas. In these patients, except for the 1 patient with adrenal cysts who had a CT value of 8 HU, very few of the remaining AI patients had a CT value less than 10 HU. Therefore, the CT value cannot be used simply as a criterion for determining the benign or malignant nature of AI, and additional imaging examinations, such as CT enhancement, MRI, and FDG-PET if necessary, should be performed immediately for AI in children.

Initial hormonal testing is also needed for functional assessment, and aldosterone secretion should also be assessed when the patient is hypertensive or hypokalemic [7]. Patients with AI who are not suitable for surgery should be observed during the follow-up period, and if abnormal adrenal secretion is detected or suggestive of malignancy during this period, prompt adrenal tumor resection is needed. For adult patients with AI, laparoscopic adrenal tumor resection is one of the most effective treatments that has comparative advantages in terms of hospitalization time and postoperative recovery speed; however, there is still some controversy over whether to perform laparoscopic surgery for some malignant tumors with large diameters, especially adrenocortical carcinomas, and some studies have shown that patients who undergo laparoscopic surgery are more prone to peritoneal seeding of tumors [10].

The maximum diameter of an adult AI is a predictor of malignancy, and a study by the National Italian Study Group on Adrenal Tumors, which included 887 AIs, showed that adrenocortical carcinoma was significantly correlated with the size of the mass, and the sensitivity of detecting adrenocortical carcinoma with a threshold of 4 cm was 93% [11]. According to the National Institutes of Health, patients with tumors larger than 6 cm should undergo surgical treatment, while patients with tumors smaller than 4 cm should closely monitored; for patients with tumors between 4 and 6 cm, the choice of whether to be monitored or surgically treated can be based on other indicators, such as imaging [12]. A diameter of 4 cm is not the initial threshold for determining the benign or malignant nature of a mass in children.

In a study of 26 children with AI, Masiakos et al. reported that 9 of 18 benign lesions had a maximal diameter less than 5 cm, 4 of 8 malignant lesions had a maximal diameters less than 5 cm, and 2 had a diameter less than 3 cm. The mean maximal diameter of benign lesions was 4.2 ± 1.7 cm, whereas the mean maximum diameter of malignant lesions was 5.1 ± 2.3 cm. There was no statistically significant difference between the two comparisons; therefore, this study concluded that children with AI diameters less than 5 cm cannot be treated expectantly [6]. Additionally, this study revealed that malignant lesions occurred significantly more frequently than benign lesions in younger children (mean age 1.7 ± 1.8 years v 7.8 ± 5.9 years; P = 0.02).

In the nonneonatal group of this study, 20 patients with malignant tumors had maximum diameters ranging from 20 to 131 mm, 10 had malignant tumors larger than 60 mm, and 3 had tumors smaller than 40 cm; 18 patients with benign tumors had maximum diameters ranging from 17 to 70 mm, 5 had diameters ranging from 40 to 60 mm, and 5 had diameters larger than 60 mm. Therefore, it is not recommended to use the size of the largest diameter of the tumor to decide whether to wait and observe or intervene surgically for children with AI. Instead, it is necessary to consider the age of the child; laboratory test results, such as whether the tumor indices are elevated or not; whether the tumor has an endocrine function; etc.; and imaging test results to make comprehensive judgments and decisions. Preoperative aggressive evaluation and prompt surgical treatment are recommended for nonneonatal pediatric AI patients.

Adrenal hematoma and NBs are the most common types of adrenal area masses in children, while pheochromocytoma, adrenal cyst, and teratoma are rarer masses [13]. In clinical practice, adrenal hematoma and NB are sometimes difficult to differentiate, especially when adrenal masses are found during the prenatal examination and neonatal period, and such children need to be managed with caution. The Children’s Oncology Group (COG ANBL00B1) implemented the watchful waiting treatment for children under 6 months of age with a solid adrenal mass < 3.1 cm in diameter (or a cystic mass < 5 cm) without evidence of distant metastasis, and if there is a > 50% increase in the adrenal mass volume, there is no return to the baseline VMA or HVA levels, or if there is a > 50% increase in the urinary VMA/HVA ratio or an inversion, surgical resection should be performed [14]. Eighty-three children in this study underwent expectant observation, 16 of whom ultimately underwent surgical resection (8 with INSS stage 1 NB, 1 with INSS stage 2B, 1 with INSS stage 4 S, 2 with low-grade adrenocortical neoplasm, 2 with adrenal hemorrhage, and 2 with extralobar pulmonary sequestration). Most of the children who were observed had a reduced adrenal mass volume. Of the 56 patients who completed the final 90 weeks of expectant observation, 27 (48%) had no residual mass, 13 (23%) had a residual mass volume of 0–1 ml, 8 (14%) had a mass volume of 1–2 ml, and 8 (14%) had a volume of > 2 ml; ultimately, 71% of the residual masses had a volume ≤ 1 ml and 86% had a residual volume ≤ 2 ml. In this study, a total of 16 patients were included in the watchful waiting treatment group; 3 patients underwent surgical treatment during the follow-up period, and 13 patients ultimately completed watchful waiting treatment. After 1–31 months of follow-up, 8 patients’ swelling completely disappeared, and 5 patients’ swelling significantly decreased. After strict screening for indications and thorough follow-up review, AIs in the neonatal period can be subjected to watchful waiting treatment, and satisfactory results can be achieved.

For benign adrenal tumors, laparoscopic surgery is superior to open surgery in terms of successful resection, whereas the feasibility of minimally invasive surgery for AI with preoperative suspicion of malignancy is controversial. The European Cooperative Study Group for Pediatric Rare Tumors recommends that minimally invasive surgery be considered only for early childhood tumors and should be limited to small, localized tumors; additionally, imaging should suggest no invasion of surrounding tissue structures or lymph nodes; and this strategy requires surgeons with extensive experience in oncologic and adrenal surgery [15]. NB is the most common pediatric AI, and open tumor resection remains the mainstay of treatment. For small, early tumors without evidence of invasion on preoperative examination, laparoscopic resection may be considered if the principles of oncologic surgery can be adhered to. If the patient responds to chemotherapy, the decision to perform laparoscopic tumor resection can also be re-evaluated after chemotherapy. According to the current study, the recurrence and mortality rates of laparoscopic surgery are comparable to those of open surgery [1617]. The relative contraindications for laparoscopic NB resection include a tumor diameter greater than 6 cm, venous dilatation, and the involvement of adjacent organs or blood vessels [18]. Patients who undergo open adrenalectomy have higher overall survival and recurrence-free survival rates than patients who undergo laparoscopic adrenalectomy [19]. Open adrenalectomy remains the gold standard for surgical resection of adrenocortical carcinoma, whereas laparoscopic adrenalectomy should be reserved for highly selected patients and performed by surgeons with appropriate expertise [20].

Cortical tumors are particularly rare among children with AIs and are sometimes not clearly distinguishable from neurogenic tumors on preoperative imaging; in such patients, the presence of subclinical Cushing’s syndrome needs to be carefully evaluated preoperatively; otherwise, a perioperative adrenal crisis may occur [21]. In patients in whom the possibility of an adrenocortical tumor was considered preoperatively, the assessment for subclinical Cushing’s syndrome mainly involved assessing the serum dehydroepiandrosterone sulfate level and performing an overnight dexamethasone suppression test.

A procedure for evaluating pediatric AI is shown in Fig. 1. Imaging is the first step in the evaluation of AI in children. CT can be used to clarify the nature of most tumors. MRI can be used to evaluate imaging risk factors (IDRFs) for NB. Bone marrow cytomorphology is recommended for all children with AI, along with microscopic residual neuroblastoma testing and further bone scanning if the bone marrow examination is positive. In addition, serum tumor marker levels and other relevant tests should be performed, and hormone levels should be evaluated. If adrenal adenomas cannot be completely excluded during the preoperative examination, a 1 mg overnight dexamethasone suppression test should be performed to exclude subclinical Cushing’s syndrome. In patients with hypertensive hypokalemia, the presence of aldosteronism should be evaluated by testing plasma aldosterone concentrations and plasma renin activity. Adrenal masses found in the neonatal period can be observed if the tumor is small, confined to the adrenal gland and shows no evidence of distant metastasis, while tumors that increase significantly in size during the follow-up period or that are associated with persistently elevated tumor markers require aggressive surgical treatment.

Fig. 1

figure 1

Algorithm for the evaluation and management of a pediatric adrenal incidentaloma. *DST overnight :20µg/kg dexamethasoneweight ˂40 kg,1 mg dexamethasone if ≥ 40 kg. CT = computed tomographic;MRI = magnetic resonance imaging;NSE = neuron-specific enolase;AFP = alpha-fetoprotein;CEA = carcinoembryonic antigen;CA19-9 = cancerantigen19-9;ACTH = adrenocorticotropic hormone;PAC = plasma aldosterone concentration; PRA = plasma renin activity;DST = dexamethasone suppression test

Data availability

The datasets analyzed during the current study are not public, but are available from the corresponding author on reasonable request.

Abbreviations

CT:
computed tomographic
MRI:
magnetic resonance imaging
ACTH:
adrenocorticotropic hormone
VMA:
vanillylmandelic acid
HVA:
homovanillic Acid
AFP:
alpha-fetoprotein
CEA:
carcinoembryonic antigen
NSE:
neuron-specific enolase
CA19-9:
cancerantigen19-9
FH:
favorable histology
HU:
Hounsfiled Unit
COG:
Children’s Oncology Group
INSS:
International Neuroblastoma Staging System

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Acknowledgements

We would like to express our deepest gratitude to all the patients and their parents who participated in this study. Their patience and cooperation were instrumental to the success of this research. We thank our colleagues in the Department of Radiology for their invaluable contributions in diagnosing and monitoring the progression of adrenal incidentalomas. We sincerely appreciate the hard work of the pathologists in diagnosing and classifying tumors, which laid the foundation for our study. Finally, we would like to thank our institution for providing the necessary resources and an enabling environment to conduct this research.

Funding

Not applicable.

Author information

Authors and Affiliations

  1. Department of Urology, Children’s Hospital of Nanjing Medical University, 72 Guangzhou Road, Nanjing, 210008, Jiangsu, China

    Xiaojiang Zhu, Saisai Liu, Yimin Yuan, Nannan Gu, Jintong Sha, Yunfei Guo & Yongji Deng

Contributions

X.J.Z. and Y.J.D designed the study; S.S.L., Y.M.Y., N.N.G., and J.T.S. carried out the study and collected important data; X.J.Z. analysed data and wrote the manuscript; Y.F.G. and Y.J.D.gave us a lot of very good advices and technical support; All authors read and approved the final manuscript.

Corresponding author

Correspondence to Yongji Deng.

Ethics declarations

Competing interests

The authors declare no competing interests.

Ethics approval and consent to participate

Ethics approval for this study was granted by the Ethics Committee of Children’s Hospital of Nanjing Medical University. Informed written consent was obtained from all the guardians of the children and we co-signed the informed consent form with their parents before the study. We confirmed that all methods were performed in accordance with relevant guidelines and regulations.

Conflict of interest

There are no conflicts of interest.

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Dexamethasone Suppression for 18F-FDG PET/CT to Localize ACTH-Secreting Pituitary Tumors

Abstract

Background

18Fluorine-Fluoro-deoxy-glucose (18F-FDG) positron emission tomography (PET) is widely used for diagnosing various malignant tumors and evaluating metabolic activities. Although the usefulness of 18F-FDG PET has been reported in several endocrine diseases, studies on pituitary disease are extremely limited. To evaluate whether dexamethasone (DEX) suppression can improve 18F-FDG PET for the localization of adrenocorticotropic hormone-secreting adenomas in the pituitary gland in Cushing’s disease (CD).

Methods

We included 22 patients with CD who underwent PET imaging before and after DEX administration. We compared the success rates of PET before and after DEX suppression, magnetic resonance imaging (MRI), and bilateral inferior petrosal sinus sampling (BIPSS). We determined the final locations of adenomas based on intraoperative multiple-staged resection and tumor tissue identification using frozen sections. Standardized uptake value (SUV) were analyzed to confirm the change of intensity of adenomas on PET.

Results

Twenty-two patients were included (age at diagnosis: 37 [13–56] years), and most were women (90.91%). Pituitary adenomas compared to normal pituitaries showed increased maximum SUV after DEX suppression but without statistical significance (1.13 versus. 1.21, z=-0.765, P = 0.444). After DEX suppression, the mean and maximum SUV of adenomas showed a positive correlation with nadir cortisol levels in high-dose DEX suppression test (Rho = 0.554, P = 0.007 and Rho = 0.503, P = 0.017, respectively). In reference sites, mean SUV of cerebellum was significantly decreased (7.65 vs. 6.40, P = 0.006*), but those of the thalamus and gray matter was increased after DEX suppression (thalamus, 8.70 vs. 11.20, P = 0.010*; gray matter, 6.25 vs. 7.95, P = 0.010*).

Conclusion

DEX suppression did not improve 18F-FDG PET/CT localization in patients with CD.

Introduction

Cushing’s disease (CD) is a rare endocrine disease that results from chronic exposure to high cortisol levels because of adrenocorticotropic hormone (ACTH)-secreting pituitary tumors and is associated with increased morbidity and mortality. It represents approximately 80% of all cases of endogenous hypercortisolism [1,2,3]. Accurate localization of primary lesions in CD leads to improved remission rates and reduced adverse events following surgery [45]. A biochemical remission rate of 90–100% has been reported when tumors are localized before surgery, but it can decrease to 50–60% when surgery is performed when the location of the tumor is unknown in patients with CD [6,7,8].

Currently, magnetic resonance imaging (MRI) is the gold standard for detecting pituitary adenomas. Nevertheless, modern MRI modalities, including dynamic or volumetric sequences, can reliably detect corticotrophic adenomas in 50–90% cases of CD [9,10,11,12]. This indicates that complementary imaging strategies are required to improve the localization of primary lesions in CD.

One of the most characteristic features of corticotrophic adenomas is a compromised response to negative glucocorticoid feedback, which defines glucocorticoid resistance [13]. ACTH activates the adrenal glands to synthesize and secrete cortisol, which in turn negatively modulates the release of ACTH from the pituitary gland and corticotrophin-releasing hormone (CRH) and vasopressin from the hypothalamus [1]. In CD, a corticotrophic tumor is only partially sensitive to the inhibitory feedback exerted by cortisol, which in turn is not regulating its own production and secretion of ACTH, resulting in both excessive ACTH and cortisol levels. Glucocorticoid resistance is caused by multiple factors including glucocorticoid receptor availability, splice variant expression and affinity, and imbalanced glucocorticoid receptor signaling [1415].

Radioactive 18 F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) often demonstrates increased fluorodeoxyglucose (FDG) uptake in nonfunctioning and hormone-secreting pituitary adenomas [16,17,18]. In large observational studies of whole-body 18F-FDG positron emission tomography (PET) scans, incidental sellar 18F-FDG uptake was found in < 1% of cases, and this sign is highly specific for pituitary adenomas [19,20,21]. 18F-FDG PET imaging can detect up to 40% of corticotropinomas, some as small as 3 mm, and the rate of PET detection of corticotropinomas can be increased by CRH stimulation [922].

Here, we evaluated whether DEX suppression could improve the localization of ACTH-secreting adenomas using 18F-FDG PET/CT in patients with CD. The rationale for this is as follows. FDG uptake of corticotrophic adenomas is less suppressed than that of normal pituitary glands after DEX suppression due to glucocorticosteroid resistance.

Materials and methods

Study design and population

In this retrospective cohort study, we enrolled all patients with CD who underwent two rounds of 18F-FDG-PET/CT before and after 8-mg DEX suppression and pituitary MRI before surgery. Total 22 patients were included in this study, of which thirteen had bilateral inferior petrosal sinus sampling (BIPSS) results. All patients were diagnosed with CD by staff of the Department of Endocrinology and/or Neurosurgery at Severance Hospital between 2014 and 2015. The diagnosis of CD was confirmed based on biochemical test results, including the cortisol, 24-hour urine free cortisol (24 h UFC), and serum ACTH levels, overnight dexamethasone suppression test (ON DST) results, and high-dose dexamethasone suppression test (HD DST) results.

Immediate remission was defined as hypocortisolism (serum cortisol level < 1.8 µg/dL) within the first 7 days after surgery. Delayed remission was defined as the achievement of hypocortisolism within 6 months, although immediate remission was not confirmed. If patients showed elevated postoperative cortisol levels and needed additional treatment within 6 months after surgery, we defined them as having persistent disease [23,24,25].

A serum cortisol concentration > 1.8 µg/dL for 8 h in the morning after 1 mg of DEX was given at midnight was considered to be a positive result in the ON DST [26]. Suppression of the serum cortisol level by > 50% for 6 h after 2 mg of DEX was administered for 2 days was defined as the suppression on the HD DST [26]. The final diagnosis was confirmed using surgical pathology and clinical follow-up.

Endocrinological evaluation

All laboratory analyses were performed at the Department of Laboratory Medicine, Severance Hospital. Preoperative cortisol and 24 h UFC were measured by chemiluminescence immunoassay using an automated UniCel DXC880i Synchron analyzer (Beckman Coulter, Pasadena, CA, USA; coefficient of variation [CV] ± 15 nmol/L at < 100 nmol/L and ± 15% at > 100 nmol/L). Preoperative ACTH levels were analyzed by electrochemiluminescence immunoassay using the Roche Cobas 6000 analyzer (Roche Diagnostics GmbH, Mannheim, Germany; CV ± 2.0 pmol/L at < 20 pmol/L and ± 10% at > 20 pmol/L).

The serum cortisol concentration at 8:00 am the following day after 1 mg of DEX was administered at midnight was considered positive on the ON DST. We determined the result as “suppression” by the cortisol level of < 1.8 µg/dL. A serum cortisol level suppressed by > 50% of the original level after 6 hourly administrations of 2 mg of DEX for 48 h was defined as suppression on the HD DST [27].

18F-FDG PET/CT evaluation

PET/CT was performed using a GEADVANCE PET scanner (GE, Milwaukee, WI, USA) after the intravenous injection of 7–9 mCi of 18F-FDG. All patients fasted for at least 6 h before the test. Emission scanning was continued for 15 min (4.25-mm axial spatial resolution, 4.8-mm transaxial spatial resolution). Transmission scans were performed for 8 min using triple Ge-68 rod sources to correct attenuation. Gathered data were reconstructed in a 128 × 128 × 35 matrix with a pixel size of 1.95 × 1.95 × 4.25 mm by means of a filtered back-projection algorithm employing a transaxial 8.5-mm Hanning filter and 8.5-mm axial ramp filter. Two specialists independently interpreted the encoded baseline PET images, and after a two-week period, they interpreted the encoded post DEX suppression PET images. Each specialist was blinded to MRI imaging, clinical characteristics, and surgical outcomes of these subjects. Each was tasked with determining whether the PET image indicated a “negative” or “positive” result for pituitary adenoma and its location on a high-resolution computer screen.

The scan after DEX suppression was performed 24 h after the oral administration of 8 mg of DEX using the same procedures as for the baseline PET/CT scan.

18F-FDG uptake analysis

The Region of interest (ROI) was drawn using MIM software (version 6.5, Software INc., Cleveland, OH, USA) (Fig. 1). PET images were reviewed by experienced by an experienced specialist. The pituitary gland was identified and a circular ROI was drawn. A fixed ROI with a 3-mm diameter was used for all patients. The ROI was placed on the lesion with the highest FDG uptake. If there was no significantly increased FDG uptake, the same sized circular ROI was drawn on the suspected adenoma location. For the normal pituitary gland, the same sized 3 mm ROI was used.

Fig. 1

figure 1

Images of ROI for pituitary adenoma on18F-FDG PET scan

Example of ROI definition in pituitary adenomas of 18F-FDG PET scan of the patients with CD. We draw the fixed circular ROI with a 3-mm diameter for pituitary adenomas (red circle) and normal pituitary gland (green circle)

ROI, Reason of interest; 18F-FDG PET, 18 F-fluorodeoxyglucose positron emission tomography; CD, Cushing disease

The mean standardized uptake value (SUVmean) and maximum SUV (SUVmax) for pituitary adenomas and normal pituitary glands were automatically measured using MIM, version 6.5 (Software Inc., Cleveland, OH, USA). The standardized uptake value (SUV) of the volume of interest was calculated as follows: (decoy-corrected activity (kBq) / volume (mL)) / (injected dose (kBq) / body weight (g)).

SUVmean and SUVmax of pituitary adenomas were divided into the SUVmean of normal pituitary glands for adjustment. We used the ratio of SUVmax to SUVmean to analyze the homogeneity of the pituitary adenomas.

MRI evaluation

All patients underwent pituitary MRI with a 3.0-Tesla scanner (Achieva, Philips Medical Systems, Best, the Netherlands). Imaging protocols included T1-weighted imaging, T2-weighted imaging, and delayed gadolinium-enhanced T1-weighted imaging. The extent, location, and sizes of the pituitary tumors were reviewed based on official records determined by radiologists.

Pituitary tumors were classified based on radiological findings using MRI of the sellar and parasellar regions. Type I refers to tumors < 1 cm in diameter limited to the sella. Type II tumors extend into the suprasellar space, < 1 cm from the diaphragm. Type III includes tumors extending into the suprasellar space > 1 cm from the diaphragm or sphenoid sinus and encroaching on the internal carotid arteries. Lastly, type IV refers to adenomas with obvious invasion into the cavernous sinus, as shown on MRI, and into the medial dural wall of the cavernous sinus, as confirmed during surgery.

BIPSS

Before surgery, BIPSS was performed to confirm the cause of CD and lateralize the tumors. A catheter was placed in patients using a unilateral femoral venous approach and 3 cc of blood was collected from the peripheral (P) and both inferior petrosal sinuses (IPS) [28]. CRH at a dose of 1 µg/kg was administered, and peripheral and petrosal samples were drawn after 5 and 10 min, respectively. The catheters and sheath were removed, and the groin was compressed under pressure until venous hemostasis was achieved.

The IPS:P prolactin ratio was calculated at each time point to confirm the accuracy of the inferior petrosal venous sampling. A value of ≥1.8 was considered successful IPS catheterization. The prolactin-normalized ACTH ratio was calculated by dividing the dominant ACTH IPS:P ratio by the concurrent and ipsilateral IPS:P prolactin ratio. A value of ≥1.3 was considered diagnostic of CD. An intersinus ACTH ratio of ≥1.4 either at baseline or after stimulation was used for lateralization of the pituitary adenoma [29].

Location of the adenoma

The final assignment of the true location of the pituitary adenoma was based on intraoperative multiple stage resection and tumor tissue identification using frozen sections. Surgically identified adenomas were histologically evaluated and stained for ACTH immunoreactivity. In cases of multiple specimens obtained during the procedure, the true location of the adenoma was assigned based on the original site of the specimen containing the adenoma [30].

Statistical analysis

Data are presented as medians (ranges) or numbers (percentages). The baseline characteristics of the patients were compared using Kruskal–Wallis’ test with Dunn’s procedure for nonparametric continuous variables. Categorical variables were compared using Fisher’s exact test. Spearman’s correlation coefficients were used to determine the correlation between FDG uptake and hormone levels. Wilcoxon’s signed-rank test was used to identify changes in the SUV after DEX administration.

The interobserver agreement for image analysis was assessed using κ statistics. κ values were categorized as follows: κ < 0.20 indicated poor agreement, κ of 0.21–0.40 indicated fair agreement, κ of 0.41–0.60 indicated moderate agreement, κ of 0.61–0.80 indicated good agreement, and κ > 0.81 indicated excellent agreement [31].

Statistical significance was set at a two-sided P < 0.05. All statistical analyses were performed using SPSS software (IBM Corp., Armonk, NY, USA).

Results

Patient characteristics

We enrolled all patients with CD who underwent two rounds of the 18F-FDG PET/CT with or without DEX suppression and sellar MRI before transsphenoidal adenectomy (TSA). Twenty-two patients were included (age at diagnosis: 37 [13–56] years), and most were women (90.91%). Patients’ baseline characteristics are shown in Table 1. There were 16 microadenomas and 6 macroadenomas. Immediate remission was achieved in 81.82% of the patients and delayed remission in 13.64%; one patient showed persistent disease after TSA. The median preoperative 24 h UFC, serum ACTH, and cortisol levels were 443.35 (93.00–4452.00) µg/day, 36.16 (6.00–92.00) pg/mL, and 18.55 (6.00–40.00) µg/dL. The size of pituitary adenomas on MRI was 7.85 (2.00–28.00) mm. The Ki-67 index of 47.06% of adenomas ranged from 1 to 2, that of 35.29% was below 1, and that of 17.65% was 2 or higher. Overall, 75.00% of the adenomas were classified as Knosp grade 0, 5.00% as grade 1, 5.00% as grade 3b, and 15.00% as grade 4. In total, 77.27% (17/22) of patients had an ACTH-staining adenoma. Only one patient showed unsuppressed cortisol levels on the HD DST.

Table 1 Patients’ imaging and clinical characteristics

MRI negative but PET positive case

Two patients showed negative MRI results, and one of them showed FDG uptakes on both 18F-FDG PET scans at baseline and after DEX suppression. A 26-year-old man visited our hospital complaining of weight gain and was diagnosed with ACTH-dependent CD. Cortisol secretion was suppressed on the HD DST; however, sellar MRI did not reveal any suspicious lesions. BIPSS revealed a central tumor (central/peripheral ACTH level of 36.25 after CRH stimulation) lateralized to the right side of the pituitary gland. The patient underwent 18F-FDG-PET/CT before and after DEX suppression to identify the primary lesions. Baseline PET/CT showed diffused FDG uptake with an SUVmax of 1.03 at the pituitary fossa but failed to localize the tumor. After DEX treatment, focal FDG uptake with an SUVmax of 1.06 remained at the right side of the pituitary fossa, which resulted in the successful localization of the corticotrophic adenoma. The MRI and PET/CT images of this case are presented in Fig. 2A–C. During TSA, the surgeon identified solid tumor-like tissues on the right side of the pituitary gland and successfully removed them. Results of pathology and ACTH immunohistochemistry were negative, but the patient achieved immediate biochemical remission and CD-related symptoms were relieved after surgery. We followed the patient for 98 months after the surgery and confirmed that he had lived without recurrence.

Fig. 2

figure 2

Images of a corticotroph with negative MRI but positive18 F-FDG PET/CT after DEX suppression

An MRI-negative adenoma was detected on 18F-FDG PET/CT at baseline and after DEX suppression. In this patient, the pituitary adenoma was visible on PET scans at baseline (B) and after DEX suppression (C) at the same location, as confirmed by the surgeon

A. Co-registered baseline 18F-FDG PET/CT and MRI images. Diffuse 18F-FDG uptake is detected in the pituitary fossa with an SUVmean of 0.86 and SUVmax of 1.03, but there was failure to localize the adenoma on baseline 18F-FDG PET/CT.

B. Co-registered 18F-FDG PET/CT and MRI images after DEX suppression. 18F-FDG uptake is not suppressed in the right side of the pituitary gland with an SUVmean of 1.03 and SUVmax of 1.06. 18F-FDG PET/CT after DEX suppression was successful in localizing the right-sided corticotrophic adenoma

C. MRI image. There is no suspicious lesion in the pituitary gland

ACTH, adrenocorticotropic hormone; MRI, magnetic resonance imaging; 18F-FDG, 18 F-fluorodeoxyglucose; PET/CT, positron emission tomography/computed tomography; DEX, dexamethasone; SUVmean, mean standardized uptake value; SUVmax, maximum standardized uptake value

Change of 18F-FDG uptake after DEX suppression

We included 18 pituitary adenomas that were successfully localized using PET/CT after DEX suppression, and analyzed the change of SUV for 15 adenomas, excluding outliers with SUV over 2.00. The results are presented in Fig. 3A and B. The SUVmean of adenomas did not changed after DEX suppression compared to normal pituitary glands (SUVmean of adenoma/SUVmean of normal pituitary glands: 1.13 [0.85–1.35] vs. 1.14 [0.87–1.39], z=-1.288, P = 0.198). DEX suppression increased SUVmax of adenomas compared to normal pituitary glands but without statistical significance (SUVmax of adenoma/SUVmean of normal pituitary glands: 1.13 [0.96–1.52] vs. 1.21 [0.97–1.56], z=-0.765, P = 0.444).

Fig. 3

figure 3

Changes in the SUVs of corticotrophs between18F-FDG PET/CT before and after DEX suppression

The SUVmean (A) and SUVmax (B) of corticotrophic adenomas are shown in this pairwise analysis. The SUVmean did not changed after DEX suppression from (z=-1.288, P = 0.198). The SUVmax of the corticotrophic adenoma increased from 1.13 to 1.21 (z=-0.765, P = 0.444). In this analysis, the SUVmean and SUVmax of pituitary adenomas were adjusted using the SUVmean of the normal pituitary gland. Colored plots and bars presented median and interquartile range in this figure. We presented the tumors with size larger than 5 mm and SUV adjusted by normal pituitary>1 for blue line

SUVmean, mean standardized uptake value; SUVmax, maximum standardized uptake value; DEX, dexamethasone; 18F-FDG, 18 F-fluorodeoxyglucose; PET/CT, positron emission tomography/computed tomography

In Fig. 3, the blue line indicates change in SUV of adenomas larger than 5 mm with higher FDG uptake than the surrounding pituitary parenchyma. For these adenomas, DEX suppression did not change the SUV (SUVmean of adenoma/SUVmean of normal pituitary glands: 1.31 [1.04–2.52] vs. 1.33 [1.05–2.38], z=-0.784, P = 0.433; SUVmax of adenoma/SUVmean of normal pituitary glands: 1.36 [1.02–2.61] vs. 1.40 [1.03–2.65], z=-1.022, P = 0.307).

The value of SUV increased in 73.33% adenomas, while the SUVmax increased in 66.67% compared with normal pituitary glands after DEX treatment.

Correlation between the hormone level and 18F-FDG uptake

Table 2 shows the results of the Spearman correlation analysis of the SUV with preoperative cortisol, ACTH, and nadir cortisol levels on the HD DST. On the baseline 18F-FDG PET scan, the SUVmax of the adenomas did not show any correlation with the levels of three hormones. The SUVmean of adenomas showed a positive correlation with nadir cortisol levels on the HD DST (P = 0.014) and preoperative ACTH levels, with marginal significance (P = 0.062). After DEX suppression, the SUVmax and SUVmean of adenomas had a positive correlation with moderate degrees of nadir cortisol on the HD DST (SUVmax: Spearman Rho = 503, P = 0.017; SUVmean: Spearman Rho = 0.554, P = 0.007).

Table 2 Correlation between FDG uptakes and hormone levels

FDG uptake of reference sites after DEX suppression

We evaluated the FDG uptake for five types of reference areas (normal pituitary gland, cerebellum, thalamus, white matter, and gray matter) (Table 3). Normal pituitary gland and white matter did not affect the unadjusted SUVmean by DEX suppression (all P >0.05). DEX significantly increased SUVmean of the thalamus and gray matter (thalamus, 8.70 [4.40–22.70] vs. 11.20 [6.40–17.5], P = 0.010*; gray matter, 6.25 [2.50–15.00] vs. 7.95 [5.00–11.90], P = 0.010*). However, SUVmean of the cerebellum significantly decreased after DEX administration (7.65 [4.50–10.80] vs. 6.40 [2.60–12.00], P = 0.006*).

Table 3 The change of FDG uptake for reference sites after DEX suppression in the patients with CD

Qualitative analysis by diagnostic modalities for CD

The qualitative results of localizing pituitary adenomas in CD patients are shown in Table 4 and Fig. 4. Only 13 patients had BIPSS results. The success rates were 90.91% for MRI and 84.62% for BIPSS.

Table 4 Qualitative analysis by diagnostic modalities for CD
Fig. 4

figure 4

Images for corticotroph adenomas that appear different for localization in18F-FDG PET/CT.

9 mm sized adenoma in the left lateral wing of pituitary gland. It was found in the left lateral wing of the pituitary gland, showing an 18F-FDG uptake in the pituitary fossa with an SUVmean of 1.04 and SUVmax of 1.07. However, after DEX suppression, the left side of the pituitary gland did not exhibit suppressed 18F-FDG uptake, with SUVmean 1.05 SUVmax 1.14

(A). Co-registered baseline 18F-FDG PET/CT and MRI images. (B). Co-registered 18F-FDG PET/CT and MRI images after DEX suppression. (C). MRI image

2 mm pituitary adenoma was detected at the left lateral wing, showing diffuse FDG uptake in the pituitary fossa with an SUVmean of 0.86 and SUVmax of 1.04. After DEX suppression, focal FDG uptake was observed, with SUVmean 0.87 and SUVmax 0.98. (D). Co-registered baseline 18F-FDG PET/CT and MRI images. (E). Co-registered 18F-FDG PET/CT and MRI images after DEX suppression. (F). MRI image

In baseline PET scans, the specialists agreed that pituitary adenomas were visible in 17 scans and not visible in 5 scans. They reached a consensus that the tumor was evident in two scans, but there was a discrepancy in their assessments of its location.

After DEX suppression, pituitary adenomas showed positive results in 16 scans and negative results in 5 scans. Specialists disagreed on the presence of pituitary adenomas in one case only.

Interobserver agreement for localizing adenomas was 0.872 (95%CI: 0.711, 1.033) for baseline PET/CT and 0.938 (95%CI: 0.762, 1.056) for post dexamethasone suppression PET/CT, confirming excellent interobserver agreements, and the result was judged reliable. Among the instances where both opinions agreed, there were no lesions that showed differences in visibility between scans before and after DEX administration. This meant that lesions were either consistently visible or invisible in both scenarios.

Discussion

We found that DEX suppression did not improve localization of ACTH-secreting pituitary adenomas using 18F-FDG PET/CT. Further, it did not significantly affect FDG uptakes in adrenocorticotrophic adenomas or normal pituitaries in patients with CD. The decision to administer 8 mg dexamethasone was based on the standard high-dose DST, which is internationally recommended for differentiating between ectopic ACTH secretion and CD [26]. This test involved comparing serum cortisol levels at 8 am before and after a single dose of 8 mg dexamethasone administered at 11 pm. Suppression of the serum cortisol level to less than 50% of the baseline value indicated a diagnosis of CD [3233]. Previous studies have reported that the 8-mg DST has a sensitivity of 90%, specificity of 100%, accuracy of 96.8%, positive predictive value of 100%, and negative predictive value of 95.5% [3435]. Our use of 8 mg dexamethasone was based on the theory that orally administering dexamethasone at this dose can effectively suppress cortisol levels in ACTH-secreting pituitary tumors.

We expected that FDG uptake by corticotrophic adenomas would not decrease after DEX administration in patients with CD, and this change may improve the ability to discriminate the tumor location from surrounding tissues on 18F-FDG PET. The SUVmax of pituitary adenomas adjusted for the normal pituitary gland increased from 1.13 to 1.21. However, this change was not statistically significant, and the success rate of localizing corticotrophic adenomas using 18F-FDG PET was not significantly improved after DEX suppression. If the FDG uptake of adenomas changed lesser compared to that of surrounding normal tissues after DEX suppression, the tumor could be more easily visualized because of the difference.

In addition, we attempted to evaluate FDG uptakes in other brain areas (cerebellum, thalamus, white matter, and gray matter) according to DEX administration in CD patients. SUVmean of the cerebellum decreased significantly, but that of the thalamus and gray matter increased after DEX suppression. DEX did not change FDG uptake in pituitary adenoma, normal pituitary, or white matter. In a previous study analyzing FDG PET in CD patients, researchers observed varying correlations between FDG uptake and blood cortisol concentration across different brain regions [3536]. Nevertheless, the examination did not include an analysis of FDG uptake in the pituitary gland. Additionally, no previous studies have explored the effects of high-dose dexamethasone suppression on brain glucose metabolism in individuals with CD. Further studies are needed to explain the change in FDG uptake after DEX administration in patients with CD.

18F-FDG PET/CT provides information regarding glucose metabolism in the brain in vivo and has been widely used to evaluate brain metabolism in clinical and research settings [37]. Here, the nadir cortisol level on the HD DST correlated with the SUVmean and SUVmax of pituitary adenomas on PET scans after DEX suppression. Cortisol secretion activity is thought to be associated with metabolic activity, and DEX administration altered this. Cortisol levels and FDG uptake in other regions of the brain are correlated in patients with CD, but the correlation between cortisol and FDG uptake in the pituitary glands and/or corticotrophic adenomas themselves has not been discussed [3536]. In our study, cortisol levels did not show a correlation with FDG uptake of corticotrophic adenomas, but after DEX suppression FDG uptake showed a correlation with the nadir cortisol level on the HD DST. This indicated that tumors in which cortisol secretion was less suppressed by on the HD DST showed higher FDG uptake than tumors with lower cortisol levels on the HD DST.

Although many studies have analyzed FDG uptake of brain tumors, reference sites defined in each study varied without a uniform standard. Gray matter, white matter, or adjacent tumor tissue was defined as a reference site [38,39,40]. We measured SUVmean of normal pituitary tissues, gray matter, white matter, thalamus, and cerebellum as possible references. We defined the SUVmean of normal pituitary tissues as a reference because the localization of adenomas requires an apparent difference between the adenoma and surrounding tissues.

Use of fixed ROI to measure FDG uptake caused partial volume effect in this study. However, lesions smaller than 5 mm with intense FDG uptake may still show increased FDG uptake, especially in tumors, albeit with lower SUV values compared with the actual values [41]. This study was performed because pituitary adenomas smaller than 5 mm with higher FDG uptake than the surrounding pituitary parenchyma have been observed in routine clinical practice. To control for the partial volume effect, the analysis was performed again for tumors which were larger than 5 mm and had higher FDG uptake than the surrounding pituitary parenchyma, and the results remained unchanged.

PET/CT has been explored as an alternative to or combined with MRI for the localization of corticotrophic adenomas. 18F-FDG PET/CT has a limited role in CD diagnosis, but CRH stimulation can increase its success rate [2242]. This study is important for increasing the effectiveness of PET using DEX. In addition, data on DEX effect on brain metabolism in patients with CD will be important for future studies.

Conclusions

DEX suppression did not improve the localization of 18F-FDG PET/CT in patients with CD. This is considered to have sufficient significance in an effort to increase the diagnostic value of 18F-FDG PET/CT.

Data Availability

All datasets generated and/or analyzed during the current study are not publicly available but are available from the corresponding author upon reasonable request.

Abbreviations

18F-FDG:
18F-fluorodeoxyglucose
PET/CT:
Positron emission tomography/computed tomography
DEX:
Dexamethasone
MRI:
Magnetic resonance imaging
BIPSS:
Bilateral inferior petrosal sinus sampling
CD:
Cushing’s disease
SUV:
Standardized uptake value
ACTH:
Adrenocorticotropic hormone
CRH:
Corticotrophin-releasing hormone
FDG:
Fluorodeoxyglucose
24hr UFC:
24-hour urine free cortisol
ON DST:
Overnight dexamethasone suppression test
HD DST:
High-dose dexamethasone suppression test
SUVmean :
Mean standardized uptake value
SUVmax :
Maximum standardized uptake value
P:
Peripheral
IPS:
Inferior petrosal sinuses
TSA:
Transsphenoidal adenectomy

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    Acknowledgements

    We would like to thank Editage (www.editage.co.kr) for English language editing.

    Funding

    The study was supported by the “Team Science Award” of Yonsei University College of Medicine (6-2022-0150).

    Author information

    Authors and Affiliations

    1. Endocrinology, Institute of Endocrine Research, Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea

      Kyungwon Kim, Cheol Ryong Ku & Eun Jig Lee

    2. Department of Radiology, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea

      Dong Kyu Kim

    3. Department of Neurosurgery, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea

      Ju Hyung Moon, Eui Hyun Kim & Sun Ho Kim

    Contributions

    Conception and design: EJL, CRK, KK. Acquisition of data: KK, DKK. Analysis and interpretation of data: KK. Drafting the article: KK. Administrative/technical/material support: JHM, EHK, SHK. Study supervision: EJL, CRK. Writing, review, and revision of the manuscript: KK, DKK, SHK, CRK. Final approval of the manuscript: CRK, EJL.

    Corresponding authors

    Correspondence to Cheol Ryong Ku or Eun Jig Lee.

    Ethics declarations

    Ethics approval and consent to participate

    The data were collected under the conditions of regular clinical care with approval from the ethics committee of our hospital, and the requirement for written informed consent was waived owing to its retrospective design (institutional review board number: 2023-0110-001).

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    The authors declare no conflicts of interest that could be perceived as prejudicing the impartiality of this study.

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    Electronic supplementary material

    Additional file 1 of Dexamethasone suppression for 18F-FDG PET/CT to localize ACTH-secreting pituitary tumors

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    Cite this article

    Kim, K., Kim, D.K., Moon, J.H. et al. Dexamethasone suppression for 18F-FDG PET/CT to localize ACTH-secreting pituitary tumors. Cancer Imaging 23, 85 (2023). https://doi.org/10.1186/s40644-023-00600-8

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    Keywords

    • 18F-FDG PET/CT
    • ACTH-secreting pituitary tumor
    • Cushing’s disease
    • Dexamethasone suppression
    • High-dose dexamethasone suppression test

    From https://cancerimagingjournal.biomedcentral.com/articles/10.1186/s40644-023-00600-8

Minimizing the Number of False Positives in Dexamethasone Suppression Testing for the Diagnosis of Cushing’s Syndrome

In this application note, Tecan presents a method for diagnosing Cushing’s syndrome efficiently and accurately. The approach involves simultaneous the measurement of cortisol and dexamethasone levels using LC-MS/MS, which reduces false positives in dexamethasone suppression test (DSTs). The described LC-MS/MS method enables the tracking of multiple analytes, including cortisol, cortisone, and dexamethasone, in serum or plasma. Implementing this analytical approach offers clinical laboratories a straightforward means of performing DSTs, and the availability of a commercially available kit ensures reliable and reproducible results.

 

CRH Stimulation Test Boosts Cushing Disease Diagnosis

The study covered in this summary was published on Research Square as a preprint and has not yet been peer reviewed.

Key Takeaways

  • Adding a corticotropin-releasing hormone (CRH) stimulation test immediately following a 2-day low-dose dexamethasone suppression test (LDDST) ― what’s known as a Dex-CRH test and was first introduced in 1993 ― identified Cushing disease in 5 of 65 people (7.7%) with a confirmed diagnosis but who had previously shown normal cortisol levels on a conventional LDDST.
  • However, the Dex-CRH test also resulted in one (2.5%) false positive case compared with an LDDST alone.
  • Measuring serum dexamethasone levels further improved the diagnostic accuracy of the Dex-CRH test.

Why This Matters

  • It can be challenging to diagnose Cushing syndrome and to differentiate Cushing disease from nonneoplastic physiologic hypercortisolism caused by conditions that can present with Cushing syndrome–like clinical features, such as diabetes and obesity.
  • The Dex-CRH test, first described in 1993, initially appeared superior to an LDDST alone for ruling out nonneoplastic hypercortisolism, with a report of 100% sensitivity, specificity, and diagnostic accuracy. However, subsequent studies that used different protocols and in which dexamethasone was not measured had results that called into question the accuracy, sensitivity, and specificity of the Dex-CRH test.
  • This study reports the accuracy, sensitivity, and specificity of the Dex-CRH test for diagnosing Cushing disease, performed as first described, in 107 patients, including 74 for whom dexamethasone was also measured.

Study Design

  • The researchers analyzed data from 107 patients with suspected Cushing disease who underwent a Dex-CRH test during 2002–2014 at the Cleveland Clinic.

Key Results

  • Sixty-five people received a confirmed diagnosis of Cushing disease and underwent follow-up for a median of 66 months. Cushing disease was not confirmed in 42 patients who were followed for a median of 52 months.
  • The median age of the 107 patients was 40 years, and 82% to 88% were women. The median body mass index for these patients was 34–37 kg/m2.
  • Among the 65 patients with confirmed Cushing disease, five patients (7.7%) had a suppressed cortisol level no greater than 1.4 μg/dL after the LDDST but were appropriately classified as having Cushing disease with a cortisol level that surpassed 1.4 μg/dL by 15 minutes after CRH stimulation.
  • In contrast, 3 of 42 patients (7.1%) in the group without confirmed Cushing disease had an abnormal Dex-CRH test result. For one of these three patients, the LDDST result was borderline normal, with a cortisol level post-DEX of 1.4 μg/dL that increased to 3.1 μg/dL by 15 minutes after CRH stimulation, which resulted in this patient receiving a false positive diagnosis.
  • A cortisol threshold value of more than 1.4 μg/dL during the Dex-CRH test was diagnostic of Cushing disease with sensitivity of 100%, specificity of 93%, and diagnostic accuracy of 97%.
  • Among the 74 patients with dexamethasone measurements, the sensitivity of the Dex-CRH test was unchanged, but the specificity and diagnostic accuracy increased to 97% and 99%, respectively.

Limitations

  • The study was retrospective.
  • Not all patients underwent measurement of dexamethasone level.
  • No uniform protocol existed for the diagnostic work-up and follow-up of patients suspected of having Cushing disease.

Disclosures

  • The study did not receive commercial funding.
  • The authors had no financial disclosures.

This is a summary of a preprint research study , “The Addition of Corticotropin-Releasing Hormone to 2-Day Low Dose Dexamethasone,” written by researchers primarily from the Cleveland Clinic and Johns Hopkins University School of Medicine, published on Research Square, and provided to you by Medscape. This study has not yet been peer reviewed. The full text of the study can be found on research square.com.

From https://www.medscape.com/viewarticle/985984