Case Report of a Prolactinoma in a Patient With a Novel MAX Mutation and Bilateral Pheochromocytomas

Pheochromocytomas are neuroendocrine tumors that can arise sporadically or be inherited as a familial disease, and they may occur in isolation or as part of a multitumor syndrome. Familial disease typically presents in younger patients with a higher risk of multifocality. Recently, the tumor suppressor MYC-associated factor X (MAX) gene has been implicated as a cause of familial isolated pheochromocytoma and paraganglioma. We describe a patient with a pituitary prolactinoma and bilateral pheochromocytomas who tested positive for a germline MAX mutation. Interestingly, the patient also had mild primary hyperparathyroidism that resolved upon resection of the pheochromocytomas despite the absence of parathyroid hormone staining in the tumors. To our knowledge, this case is the first report of prolactinoma in a patient with a MAX mutation, which suggests the possibility of germline MAX mutations also contributing to the development of prolactinomas.