Endocrine Abstracts

Introduction: Pheochromocytomas are rare tumors arising from adrenomedullary chromaffin cells. Pheochromocytomas are a serious clinical condition and undiagnosed cases are associated with increased unexpected cardiovascular mortality.

Case report: A female Caucasian patient aged 52-year-old was referred to the endocrine department of a public central hospital because of an incidental right adrenal mass first found 3 years before during the work out of non specific tiredness. Annual CT CT scans documented significant growth (34, 40 and 62 mm) of a hypodense lesion (less than 10 Housefield units). Presently the patient denied gastrointestinal or abdominal complaints and did not present clinical evidence for hypercortisolism, hyperaldosteronism, hyperandrogenism or for excessive catecolamine production. Past medical history revealed chronic gastritis treated with omeprazole daily. She reported three uneventful pregnancies 25, 20 and 19 years ago. Physical examination was unremarkable, with normal blood pressure and no orthostatic hypotension. Analytic evaluation excluded hypercortisolism and hyperaldosteronism. Urinary metanephrine and normetanephrine were high (12 and 16 times higher than the upper limit of the reference range) and dopamine 1.5 times over the upper limit. Serum calcium and calcitonin were in the reference range. ¹²³I-MIBG scintigraphy presented increased right adrenal uptake. Uneventful laparoscopic right adrenalectomy was performed after preoperative treatment with doxazosin 8 mg, 2 l normal saline ev and propranolol 30 mg daily. Histologic evaluation confirmed a 55 mm pheochromocitoma, with no signs of malignancy. No genetic study was conducted.

Discussion and conclusion: About 7% of adrenal incidentalomas are pheochromocytomas. Although rare, clinically silent pheocromocytomas are recognized. Possible mechanisms may include 1) vasodilator peptides co-secreted by pheochromocytomas such as dopamine; 2) desensitization of target organs due to high catecholamine long-term exposure, 3) low circulatory volume in these patients and 4) malignancy with undifferentiation and minimal catecholamine production. This case highlights the need to exclude catecholamine producing tumors in all adrenal incidentalomas, even if they are asymptomatic.