Case Report of Bilateral Pheochromocytomas due to a Novel Max Mutation in a Patient Known to have a Pituitary Prolactinoma

ABSTRACT Objective: To report on a patient with a known pituitary prolactinoma also found to have bilateral pheochromocytomas due to a novel germline MAX (MYC-associated factor X) gene mutation. Methods: Case report and literature review. Results: This patient was a 39-year-old female who presented with a 2-year history of episodes of sweating, palpitations, and elevated blood pressure. She had no family history of pheochromocytoma or paraganglioma syndromes. Her past medical history was significant for a pituitary prolactinoma diagnosed 6 years prior and well controlled with cabergoline. Bloodwork showed serum normetanephrine at 6,238 pg/mL (reference range, <148 pg/mL), serum metanephrine at 388 pg/mL (reference range, <57 pg/mL), and parathyroid hormone at 69.8 pg/mL (reference range, 10 to 65 pg/mL). Imaging revealed bilateral adrenal masses with significant uptake on nuclear imaging. Genetic testing was positive for a novel germline MAX gene mutation at c.171+2T>A. Bilateral adrenalectomy normalized all bloodwork and symptoms. Conclusion: To our knowledge, this is the fifth reported case of an association between a pheochromocytoma and pituitary adenoma—three with a prolactinoma and two with acromegaly—in patients with a germline MAX mutation. This supports the possibility of a MAX gene mutation being the cause for a syndromic disease. Abbreviations: MAX = MYC-associated factor X; MIBG = metaiodobenzylguanidine; PCC = pheochromocytoma; PGL = paraganglioma; TH = parathyroid hormone; SDH = succinate dehydrogenase