Pseudo-pheochromocytoma due to obstructive sleep apnea: a case report

SUMMARY

Obstructive sleep apnea (OSA) is a condition of intermittent nocturnal upper airway obstruction. OSA increases sympathetic drive which may result in clinical and biochemical features suggestive of pheochromocytoma. We present the case of a 65-year-old male with a 2.9-cm left adrenal incidentaloma on CT, hypertension, symptoms of headache, anxiety and diaphoresis, and persistently elevated 24-h urine norepinephrine (initially 818 nmol/day (89-470)) and normetanephrine (initially 11.2 µmol/day (0.6-2.7)). He was started on prazosin and underwent left adrenalectomy. Pathology revealed an adrenal corticoadenoma with no evidence of pheochromocytoma. Over the next 2 years, urine norepinephrine and normetanephrine remained significantly elevated with no MIBG avid disease. Years later, he was diagnosed with severe OSA and treated with continuous positive airway pressure. Urine testing done once OSA was well controlled revealed complete normalization of urine norepinephrine and normetanephrine with substantial symptom improvement. It was concluded that the patient never had a pheochromocytoma but rather an adrenal adenoma with biochemistry and symptoms suggestive of pheochromocytoma due to untreated severe OSA. Pseudo-pheochromocytoma is a rare presentation of OSA and should be considered on the differential of elevated urine catecholamines and metanephrines in the right clinical setting.

LEARNING POINTS

Obstructive sleep apnea (OSA) is a common condition among adults. OSA may rarely present as pseudo-pheochromocytoma with symptoms of pallor, palpitations, perspiration, headache, or anxiety. OSA should be considered on the differential of elevated urine catecholamines and metanephrines, especially in patients with negative metaiodobenzylguanidine (MIBG) scan results.

Adrenocorticotropic hormone (ACTH) independent Cushing's syndrome due to unilateral adrenocortical hyperplasia: two case reports

Adrenal unilateral macronodular hyperplasia is a rare cause of Cushing's syndrome. We discuss the case of two patients who present Cushing syndrome due to unilateral adrenal hyperplasia. They presented the signs of clinical hypercorticism as well as metabolic, cardiovascular and osteoporotic complications. Both patients presented clinical and laboratory signs of adrenocorticotropic hormone (ACTH)-independent Cushing syndrome with elevated urinary free cortisol (UFC) levels, adrenal computed tomography (CT) scan revealed the appearance of unilateral adrenal adenoma and normal contralateral adrenal gland. Adrenalectomy was performed under laparoscopic surgery; the resected mass was pathologically diagnosed as unilateral nodular adrenal hyperplasia. Unilateral adrenal hyperplasia is a very rare etiology of ACTH-independent Cushing syndrome, often mistaken for adenoma on CT and only pathological examination can confirm the diagnosis.

Cushing syndrome caused by adrenocortical tumors and hyperplasias (corticotropin- independent Cushing syndrome)

Endogenous Cushing syndrome (CS) is caused by excess adrenal glucocorticoid secretion that is adrenocorticotropin (ACTH)-dependent or independent; ACTH-independent adrenocortical causes of CS account for up to 20% of CS in adults, and 15% in children over age 7 years. In younger children, ACTH-independent CS may account for as many as half of the CS cases. In both adults and children, adrenocortical lesions causing CS include the common, isolated and sporadic, solitary cortisol-producing adenoma, the rare adrenocortical cancer, and a spectrum of recently recognized, bilateral hyperplasias (bilateral adrenocortical hyperplasias, BAHs): micronodular adrenal disease and its pigmented variant, primary pigmented nodular adrenocortical disease are mostly genetic processes. Macronodular BAHs, ACTH-independent macronodular hyperplasia or massive macronodular adrenocortical disease are less frequently genetic and almost never present in children (except in McCune-Albright syndrome); they present often with atypical CS in middle-aged or elderly adults. The majority of benign adrenocortical tumors associated with CS are associated with defects of the cAMP signaling pathway, whereas adrenal cancer is linked to aberrant expression of growth factors and germline or somatic mutations of tumor suppressor genes such as TP53. Adrenalectomy is the preferred mode of treatment for all adrenocortical causes of CS.