Multimodality imaging of bilateral pheochromocytoma: A case report

INTRODUCTION: Bilateral pheochromocytomas ( PHEO ) are rare, often hereditary and linked to a germline mutation of RET, VHL or SDHx. They also occur sporadically. PRESENTATION OF CASE: We report a case of a 76 year old female hospitalized for biological investigations following symptoms of abdominal discomfort with recurrent hypertensive episodes. The hormonal work up results favoured a diagnosis of a PHEO (urinary and plasma metanephrines < 10 times normal). Radiological investigations (CT-MRI): identified bilateral adrenal masses (47 mm in the right adrenal, 26 mm in the left adrenal). Functional imaging with 123 I-MIBG scintigraphy showed intense uptake in the right adrenal mass with limited uptake in the left, probably related to a fixation of the normal adrenal medulla. Due to the strong suspicion of bilateral PHEO, further imaging with an 18F-FDOPA PET was performed. This revealed intense hypermetabolism of the right mass but the left mass had similar metabolism to the liver, thought to be unsuspicious for a PHEO. It was decided to proceed with a laparoscopic right adrenalectomy. Hormonal investigations performed post-operatively revealed persistently elevated metanephrines. An 18FFDG PET was performed, revealing an intense hypermetabolic focus in the left adrenal gland. A laparoscopic partial left adrenalectomy was subsequently performed 6 weeks after the initial right adrenalectomy. DISCUSSION AND CONCLUSIONS: This case highlights the possibility of false negative results using specific functional imaging. In these situations, 18F-FDG PET may be useful.The MRI signal has an indisputable value. Until today, no germline mutation was found in this patient.