CushieBlog

Cushing’s syndrome is a condition that originates from excessive production of glucocorticoids. The condition is most common in women of childbearing age and is characterized by altered distribution of the adipose tissue to the central and upper regions of the trunk (central obesity and buffalo hump), face (moon face), capillary wall integrity (easy bruising), hyperglycemia, hypertension, mental status changes and psychiatric symptoms, muscle weakness, signs associated with hyperandrogenism (acne and hirsutism), and violaceous striae among other signs. Hypercortisolism and hyperandrogenism suppress the production of the pituitary gonadotropins, which in turn leads to menstrual irregularities and infertility.^1–3 Moreover, the main common cause of developing Cushing’s syndrome is the use of exogenic steroid.³

Cushing’s disease is a form of Cushing’s syndrome with overproduction of adrenocorticotropic hormone (ACTH) due to pituitary adenoma. The diagnosis is made using clinical features and paraclinical tests including urinary free cortisol (UFC), serum ACTH, dexamethasone suppression tests (DSTs), pituitary magnetic resonance imaging (MRI), and sometimes by inferior petrosal sinus sampling (IPSS).⁴ Although women with Cushing’s disease are less likely to become pregnant, timely diagnosis and appropriate management are especially important during possible pregnancy, preventing neonatal and maternal complications and death. The diagnosis is challenging due to the overlap of the disease symptoms with the changes associated with a normal pregnancy. Moreover, the hormonal milieu during pregnancy has recently been proposed as a potential trigger for Cushing’s disease in some cases; hence, the term “pregnancy-associated Cushing’s disease” has been used for the disease in the recent literature. In this study, we presented a thin 31-year-old woman who was referred to our clinic 2 months after a normal delivery, with an atypical presentation of Cushing’s disease, unusual clinical features, and a challenging clinical course.

Our patient was a 31-year-old woman who presented 2 months after the delivery of her second child. She had a history of type 2 diabetes mellitus and hypertension in the past 2 years prior to her presentation. She had been admitted to another center following an episode of falling and muscle weakness. Two weeks later, she was admitted to our center with an impression of pulmonary thromboembolism due to tachypnea, tachycardia, and dyspnea. During follow-up, she was found to have leukocytosis, hyperglycemia (random blood sugar: 415 mg/d; normal level: up to 180 mg/dL) and hypokalemic metabolic alkalosis (PH: 7.5, HCO₃ [bicarbonate]: 44.7 mEq/L, paO₂ [partial pressure of oxygen]: 73 mm Hg, pCO₂: 51.7 mm Hg, potassium: 2.7 mEq/L [normal range: 3.5-5.1 mEq/L]), which was refractory to the treatment; therefore, an endocrinology consultation was first requested. On physical examination, the patient was agitated, confused, and psychotic. Her vital signs were: blood pressure 155/100 mm Hg, heart rate: 130 bpm, and respiratory rate: 22 bpm, temperature: 39°C. As it has shown in Figure 1A, her face is not typical for moon face of Cushing’s syndrome, but facial hirsutism (Figure 1A) and generalized hyperpigmentation is obvious (Figure 1A-C). She was a thin lady and had a normal weight and distribution of adiposity (Body Mass Index [BMI] = 16.4 kg/m²; weight: 40 kg, and height: 156 cm). Aside from thinness of skin, she did not have the cutaneous features of Cushing’s syndrome (e.g. purpura, acne, and violaceous striae) and did not have supraclavicular and dorsocervical fat pad (buffalo hump), or plethora. In other words, she had no clinical discriminatory features of Cushing’s syndrome despite the high levels of cortisol, as confirmed by severely elevated UFC (5000 μg/24 h and 8000 μg/24 h; normal level: 4-40 μg/24 h). In addition, as will be mentioned later, the patient had axonal neuropathy which is a very rare finding in Cushing’s syndrome.

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She had a markedly diminished proximal muscle force of 1 out of 5 across all extremities; the rest of the physical examinations revealed no significant abnormalities (Figure 1B). On the contrary, based on her muscle weakness, hirsutism, psychosis and hyperpigmentation and refractory hypokalemic alkalosis, hyperglycemia, and hypertension, Cushing’s syndrome was suspected; therefore, 24-hour UFC level was checked that the results showed a severely elevated urinary cortisol (5000 μg/24 h and 8000 μg/24 h; normal level: 4-40 μg/24 h). Serum ACTH level was also inappropriately elevated (45 pg/mL; normal range: 10-60 pg/mL). High-dose dexamethasone failed to suppress plasma cortisol level and 24-hour urine cortisol level. A subsequent pituitary MRI showed an 8-mm pituitary mass, making a diagnosis of Cushing’s disease more probable. Meanwhile, the patient was suffering from severe muscle weakness that did not improve after the correction of hypokalemia. Then, a neurology consultation was requested. The neurology team evaluated laboratory data as well as EMG (Electromyography) and NCV (Nerve Conduction Velocity) of the patient, and based on their findings, “axonal neuropathy” was diagnosed for her weakness; so they ruled out the other neuromuscular diseases. A 5-day course of intravenous immunoglobulin (IVIG) was started for her neuropathy; however, the treatment did not improve her symptoms and the patient developed fungal sepsis and septic shock. Therefore, she was processed with broad-spectrum antibiotics and antifungal agents and recovered from the infection.

Mitotane was started for the patient before definitive surgical treatment to suppress hormonal production due to her poor general condition. Despite the 8-mm size of the pituitary mass which is likely to be a source of ACTH, our patient was underweight and showed the atypical clinical presentation of Cushing’s disease, making us suspect an ectopic source for the ACTH. Therefore, a Gallium dotatate scan was performed to find any probable ectopic sources; however, the results were unremarkable. The patient underwent Trans-Sphenoidal Surgery (TSS) to resect the pituitary adenoma because it was not possible to perform IPSS in our center. Finally, the patient’s condition including electrolyte imbalance, muscle weakness, blood pressure, and hyperglycemia started to improve significantly. The pathologist confirmed the diagnosis of a corticotropic adenoma. Nevertheless, the patient suddenly died while having her meal a week after her surgery; most likely due to a thromboembolic event causing a cardiac accident.

Our patient was significantly different from other patients with Cushing’s disease because of her atypical phenotype. She was unexpectedly thin and had psychosis, hyperpigmentation, proximal myopathy, axonal neuropathy and no clinical discriminatory features of Cushing’s syndrome such as central adiposity, dorsocervical or supraclavicular fat pad, plethora or striae. She had also a history of type 2 diabetes and hypertension 2 years before her admission. The patient was diagnosed with Cushing’s later. From what was presented, the patient did not know she had Cushing’s until after her delivery and despite the highly elevated UFC, and she completed a normal-term delivery. Given that she only presented with psychosis and proximal myopathy, her pregnancy was considered unusual. Her clinical features such as hyperpigmentation and severe muscle weakness are among less common presentations.⁵

11β-hydroxysteroid dehydrogenase type 1 (11-βHSD1) is an enzyme responsible for converting cortisone (inactive glucocorticoid) into cortisol (active). It is speculated that this enzyme has a role in obesity (Figure 2).^6,7

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In a case reported by Tomlinson, a 20-year-old female was diagnosed with Cushing’s disease despite not having the classical features of the disease. It has been suggested that the mechanism is a partial defect in 11β-HSD1 activity and concomitant increase in cortisol clearance rate. Thus, the patient did not have a classic phenotype; the defect in the conversion of cortisone to cortisol rises cortisol clearance and protects the patient from the effects of cortisol excess. This observation may help explain individual susceptibility to the side effects of glucocorticoids.⁶

Further studies of Tomlinson et al showed that a deficit in the function of (and not a mutation related to) 11β-HSD2 might have been responsible for the absence of typical Cushing’s symptoms. 11-HSD2 keeps safe the mineralocorticoid receptor from excess cortisol. Mutation in the HSD11B2 gene explains an inherited form of hypertension, apparent mineralocorticoid excess syndrome, in which Cushing’s disease results in cortisol-mediated mineralocorticoid excess affecting the kidney and leads to both hypokalemia and hypertension.⁸

It is frequent in Cushing’s syndrome that the patients usually have no mineralocorticoid hypertension; however, it is still proposed that a defect in 11β-HSD1 can be responsible for the presence of mineralocorticoid hypertension in a subgroup of patients. In fact, 11β-HSD1 is expressed in several tissues like the liver, kidneys, placenta, fatty tissues and gonads,⁹ meaning that this enzyme may potentially affect the results of cortisol excess in Cushing’s syndrome/disease. Abnormality in the function of this enzyme could explain the absence of the symptoms like central obesity, easy bruising, and typical striae during Cushing’s disease. Several factors affect the action of glucocorticoids. In this regard, the impact of the different types and levels of impairment in glucocorticoid receptors have been highlighted in some studies, as it can lead to different levels of response to glucocorticoids¹⁰ as well as a variety in the symptoms observed in Cushing’s disease.

The predominant reaction of the NADP(H)-dependent enzyme 11-Tukey’s honestly significant difference (HSD)1 happens through the catalysis of the conversion of inactive cortisol into receptor-active cortisol. The reverse reaction is mediated through the unidirectional NAD-dependent 11-HSD type 2 (Figure 2).¹¹

In another case reported by Ved V. Gossein, a 41-year-old female was evaluated for hirsutism and irregular menstrual cycles. Her BMI was 22.6 kg/m². The patient had no signs or symptoms of overnight recurrent Cushing’s syndrome, the 48-hour DST failed to suppress cortisol levels, and 24-hour urinary cortisol levels were persistently elevated on multiple occasions. Adrenocorticotropic hormone levels were unreasonably normal, suggesting ACTH-dependent hypercortisolism. Despite these disorders, she had 2 children. Magnetic resonance imaging (MRI) of the pituitary did not show any abnormalities. Moreover, abdominal MRI did not show adrenal mass or enlargement. Genetic testing to determine glucocorticoid resistance syndrome showed no mutation.¹²

Primary generalized glucocorticoid resistance is a rare genetic disorder characterized by generalized or partial insensitivity of target tissues to glucocorticoids.^13–17 There is a compensatory increase in hypothalamic-pituitary activity due to decreased sensitivity of peripheral tissues to glucocorticoids systems.^13–17 Excessive ACTH secretion leads to high secretion of cortisol and mineralocorticoids and/or androgens. However, the clinical features of Cushing’s syndrome do not develop after resistance to the effects of cortisol. Generalized glucocorticoid resistance is a rare condition characterized by high cortisol levels but no scarring of Cushing’s syndrome.¹⁸

An important aspect of our case was her pregnancy. Our patient had a history of hypertension and diabetes type 2, 2 years before her presentation to our center that could be because of an undiagnosed Cushing’s disease. The patient’s pregnancy terminated 2 months prior the admission and she had a normal vaginal delivery. So, we suspect that she become pregnant while involved with the disease. Aside from focusing on how this can happen in a patient with such high levels of glucocorticoids, more attention should be paid to occurring pregnancy in the background of Cushing’s disease. In fact, up to 250 patients were reported, of which less than 100 were actively treated.^19–22

Cushing’s disease is associated with serious complications in up to 70% of the cases coinciding with pregnancy.²¹ The most frequent maternal complications reported in the literature are hypertension and impaired glucose tolerance, followed by preeclampsia, osteoporosis, severe psychiatric complications, and maternal death (in about 2% of the cases). Prematurity and intrauterine growth retardation account for the most prevalent fetal complications. Stillbirth, intrauterine deaths, intrauterine hemorrhage, and hypoadrenalism have also been reported.²³ Early diagnosis is especially challenging during pregnancy because of many clinical and biochemical shared features of the 2 conditions.^23,24 These features include an increase in ACTH production, corticosteroid-binding globulin (CBG) 1 level, level of cortisol (urinary, plasma and free), hyperglycemia, weight gain, and an increased chance for occurrence of bruising, hypertension (mistaken with preeclampsia), gestational diabetes mellitus, weight gain, and mood swings.³ There are some suggestions proposed in the studies that help in screening and differentiation of Cushing’s from the normal and abnormal effects of pregnancy and Cushing’s disease from Cushing’s syndrome in suspected pregnant patients. Contrary to Cushing’s syndrome, the nocturnal minimum level of cortisol is preserved in pregnancy.^23,25 There is not yet a diagnostic cut-off determined on mentioned level; however, a few studies elucidate the evaluation of hypercortisolemia in a pregnant patient.^26–28

Urinary free cortisol, a measure that reflects the amount of free cortisol in circulation, normally increases during pregnancy, and it can increase up to 8 times the normal level with Cushing’s disease during the second and the third trimesters,^23,29 which is a useful tool to evaluate cortisol levels in a suspected pregnant woman. Because the suppression of both UFC and plasma cortisol is decreased in pregnancy,^23,30 a low-dose DST is not very helpful for screening Cushing’s disease in pregnant patients. However, a high-dose DST with a <80% cortisol suppression might only indicate Cushing’s disease.^3,31 Thus, it helps differentiating between ectopic ACTH syndrome and Cushing’s disease.³² The use of high-dose DST can distinguish between adrenal and pituitary sources of CS in pregnancy. Owing to the limited evidence available and the lack of data on normal pregnancies, the use of corticotropin-releasing hormone (CRH), desmopressin, and high-dose DST in pregnancy is not recommended yet.³³ More timely diagnosis as well as timely intervention may have saved the life of our patient.

To differentiate between ectopic ACTH syndrome and Cushing’s disease, adrenal imaging should be considered. For higher plasma levels, combined employment of CRH stimulation test and an 8-mg DST can be helpful.³ Bilateral inferior petrosal sinus sampling (B-IPSS) might be needed when the findings are not in accordance with other results, but it is recommended to perform B-IPSS only if the noninvasive studies are inconclusive and only if there is enough expertise, experience, and technique for its performance.³

Although axonal neuropathy has been reported as a rare syndrome associated with paraneoplastic ectopic Cushing’s syndrome and exogenous Cushing’s syndrome, its association with Cushing’s disease has not been reported.^5,32 Our patient had severe muscle weakness that we initially attributed it to myopathy and hypokalemia associated with Cushing’s syndrome. In our study, the diagnosis of axonal neuropathy was made based on electrophysiological studies by a neurology consultant and then IVIG was administered; however, the patient’s weakness did not improve after this treatment. The co-occurrence of Guillain-Barré syndrome which may also be classified as axonal neuropathy has also been reported in a pregnant woman with ectopic Cushing’s syndrome.^34,35 Whether this finding is coincidental or the result of complex immune reactions driven by Cushing’s disease, or the direct effect of steroids, these results cannot be deduced from current data.³⁶ Some data suggest that the fluctuations and inferior petrosal sinus sampling may trigger the flare of autoimmune processes, specifically when the cortisol levels start to decline during the course of Cushing’s syndrome.^35,8 Also, due to COVID-19 pandemic affecting vital organs like kidney, paying attention to COVID-19 is suggested.^37–40

We presented a thin young female with psychosis, proximal myopathy, and axonal neuropathy with Cushing’s disease who had a recent pregnancy that was terminated without any fetal or maternal complications despite the repeated elevated serum cortisol and 24-hour UFC; therefore, we suggest that she might have glucocorticoid resistance. Glucocorticoid resistance is a rare disease in which the majority, but not all, of patients have a genetic mutation in the hGR-NR3C1 gene. As we did not perform genetic testing for our patient, the data are lacking.

Another clue to the absence of the classic Cushing’s disease phenotype in our case is the role of isoenzymes of 11-HSD1 and 11-HSD2. Other mechanisms, such as the defect somewhere in the glucocorticoid pathway of action such as a decreased number of receptors, a reduction in ligand affinity, or a postreceptor defect, play an important role in nonclassical clinical manifestations of Cushing’s syndrome.

The authors thank the patient for allowing us to publish this case report. The authors show their gratitude to the of the staff of the Rasool Akram Medical Complex Clinical Research Development Center (RCRDC) specially Mrs. Farahnaz Nikkhah for its technical and editorial assists.

Our institution does not require ethical approval for reporting individual cases or case series.

Written informed consent was obtained from the patient and for her anonymized information to be published in this article.

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

The author(s) received no financial support for the research, authorship, and/or publication of this article.