Endocrine Abstracts

Introduction: Pheochromocytomas are rare catecholamine-secreting tumors, primarily arising from the adrenal medulla, typically presenting with hypertension, palpitations, and headaches. Diagnosis involves hormonal evaluation and CT imaging with a washout of <40-60%. Recent studies show exceptions, with some tumours mimicking non-functional adenomas, displaying >60% washout. We present a case exemplifying this, where a symptomatic patient had normal initial biochemical tests but a CT washout of 64%, initially diagnosed as an ‘adrenal incidentaloma’, later proven otherwise.

Case Presentation: A 29-year-old female presented with dizziness, headaches, and palpitations for 3-4 months. Initial investigations, including plasma and urinary catecholamines and vanillylmandelic acid levels, were normal. Two years later, she presented with vague abdominal pain. CT scans revealed a 32 x 36 x 51 mm lesion in the right adrenal gland with 64% washout, suggesting a non-functional adenoma. One year later, she was admitted to another emergency department with typical presentation of pheochromocytoma - intractable vomiting, palpitations and hypertension. Plasma metanephrines and cortisol levels were markedly elevated. After treatment with alpha blockade, she symptomatically recovered following a one-week in-patient stay. Echocardiography during in-patient stay showed stress-induced cardiomyopathy which fully recovered on cardiac MRI performed a week later. Metaiodobenzylguanidine scan demonstrated intense radiotracer accumulation in the right adrenal lesion, increased in size up to 6.0 cm, confirming the diagnosis of pheochromocytoma. The patient subsequently underwent a successful laparoscopic adrenalectomy. Cytology was positive for pheochromocytoma. Genetic testing was negative for familial catecholamine secreting syndromes. Postoperative recovery was uneventful, with adrenalectomy leading to normalization of metanephrines.

Discussion: Despite normal early biochemistry and a non-typical CT scan for pheochromocytoma, our patient’s symptoms recurred, eventually showing biochemical and radiological evidence in line with pheochromocytoma. This case emphasizes the importance of monitoring symptomatic patients for pheochromocytoma despite atypical CT findings. Prompt identification and treatment are crucial to prevent serious morbidity and mortality.