Endocrine Abstracts

Background: Multiple Endocrine Neoplasia type 1 (MEN1) is a rare hereditary endocrine cancer syndrome characterized by tumors predominantly affecting the parathyroid glands (95%), gastroenteropancreatic tract (30-80%), and anterior pituitary (15-90%)(1). We present a case of MEN1 initially manifesting with headaches and visual symptoms due to an aggressive macroprolactinoma.

Case Presentation: A 39-year-old male presented in 2018 with headache and visual disturbances. MRI revealed a 33x31x24mm pituitary lesion with optic chiasmal compression, suprasellar and left parasellar extension, encasing bilateral internal carotid arteries. Initial investigations showed markedly elevated prolactin (28,267 mIU/L) and hypogonadotropic hypogonadism. Though Concurrent hypercalcemia with inappropriately normal parathyroid hormone levels was initially overlooked but later led to diagnosis of Primary Hyperparathyroidism. PHPT diagnosis was supported by elevated 24-hour urinary calcium. The patient reported multiple renal stones since youth. DEXA scan excluded osteoporosis.

Management: One year of dopamine agonist therapy showed poor response (prolactin 9,055 mIU/L), necessitating transsphenoidal resection. Histopathology confirmed a lactotroph adenoma. Post-operatively, despite continued cabergoline, prolactin remained elevated (3,000-4,000 mIU/L). Testosterone replacement was initiated for hypogonadism. The combination of resistant macroprolactinoma and primary hyperparathyroidism prompted MEN1 genetic testing. Further investigations revealed mildly elevated gastrin (48 pmol/L) and an incidental non-functional 1.6cm adrenal adenoma. Despite negative parathyroid localization, the patient underwent successful parathyroid exploration in May 2024.

Discussion and Conclusion: This case highlights the importance of systematic endocrine screening in patients with pituitary tumors, particularly when accompanied by hyperparathyroidism. Early recognition of MEN1 syndrome specially in young patients with resistant macroprolactinomas is crucial for appropriate surveillance and management of concurrent endocrine neoplasms.

Reference: 1. Gibril F, et al. Medicine (Baltimore).