Giant Invasive Prolactinoma Presenting with Unilateral Exophthalmos in a Patient with MEN1

ABSTRACT Objective: Management of an unusual case of a giant invasive prolactinoma in a patient with multiple endocrine neoplasia type 1 (MEN1). Methods: We present complete clinical presentation, imaging, and biochemical features from a unique case of a giant invasive prolactinoma. Results: We report an unusual case of a giant invasive prolactinoma in a 29-year-old man presenting with right eye exophthalmos, headache, and bitemporal vision loss. Magnetic resonance imaging revealed a large sellar mass with suprasellar extension and extension into the right orbit. An endocrine work-up revealed elevated serum prolactin (32,000 ng/mL). On screening, the patient had high serum calcium, low phosphorous, and high parathyroid hormone. A computed tomography scan from neck to pelvis showed an enlarged left inferior parathyroid gland and bilateral renal calculi. The patient was genetically confirmed to have a MEN1 mutation. The patient was treated with the long-acting dopamine agonist, cabergoline, with escalating ...