Bilateral pheochromocytoma as a late presentation of neurofibromatosis type 1.

Summary: Neurofibromatosis type 1 (NF1) is an autosomal dominant condition predisposing to tumors, including pheochromocytomas and paragangliomas. Reported penetrance is close to 100%, but clinical presentation is highly variable. We present a case of a 79-year-old woman with an atypical and late presentation of NF1 with bilateral pheochromocytomas. She presented with long-standing abdominal pain. Her medical history included takotsubo cardiomyopathy and two episodes of intraoperative cardiogenic shock, 12 and 19 years before. A CT-scan revealed a 61 mm mass in the left adrenal gland (spontaneous density of 39 HU (hounsfield units)) and a 12 mm mass in the right adrenal gland (43 HU). The MIBG (metaiodobenzylguanidine) scan demonstrated high uptake in the left adrenal gland lesion. Urinary fractionated metanephrines were elevated. She underwent a left adrenalectomy, and pathology findings revealed a composite pheochromocytoma-ganglioneuroma. Genetic testing disclosed a pathogenic variant in the NF1 gene. After surgery, urinary fractionated metanephrines normalized but became elevated again one year later. She underwent a right adrenalectomy, and pathology confirmed a 'typical' pheochromocytoma. Other than bilateral pheochromocytoma, the patient had no other clinical manifestations of NF1, including café-au-lait macules or cutaneous neurofibromas. This case highlights the importance of offering genetic testing to all patients with pheochromocytoma, which may reveal cases of NF1 with subtler and atypical clinical presentation. Learning points: Genetic testing should be offered to all patients with pheochromocytoma. Bilateral pheochromocytomas should raise suspicion for an underlying genetic syndrome, even in elderly patients or those without a known family history. Some patients with neurofibromatosis type 1 (NF1) may have a later and subtler presentation, including isolated pheochromocytoma.