SUN-265 Lung Carcinoid Tumor as an Unusual Presentation in a Puerto Rican Patient with MEN1

Abstract Disclosure: A.C. Cotto-Vazquez: None. L. Rodriguez-Franco: None. O. Mora-Osoria: None. K.N. Yelton Torres: None. L. Salgado-Romero: None. A. Nieves-Rivera: None. C. Rosario-Martinez: None. J.M. Garcia-Mateo: None. Background:Multiple Endocrine Neoplasia 1 (MEN1) is a rare autosomal dominant syndrome with predominance for specific endocrine tumors associated with parathyroid glands, anterior pituitary, and pancreatic islet cells. Lung carcinoid tumors are uncommon and typically develop on their own. They rarely occur in connection with MEN1. Case:We present a case of a 50-year-old male that comes for an evaluation of persistent hypercalcemia. The patient's medical history indicated a diagnosis of an unspecified lung tumor and asthma. After the evaluation of laboratory workup and imaging, primary hyperparathyroidism (PHPT) was established with confirmation of right inferior parathyroid adenoma after minimally invasive parathyroidectomy. At follow up, the patient continued with persistent PHPT. Exploratory neck surgery revealed left superior parathyroid adenoma. The recurrence of PHPT instigated closer inspection into the history of his pulmonary tumor with suspicion of a neuroendocrine etiology. Following a pathology review, a lung carcinoid tumor was confirmed indicating an association with MEN1. Family history assessment revealed his mother had been treated for PHPT, pituitary tumor and pancreatic/liver cancer, with genetic confrimation of MEN1. In addition, the patient’s son presented at the age of 23 with parathyroid adenoma. Because of concerns related to medical insurance and costs, the patient did not undergo MEN1 genetic testing at this time. Over the following years, he was regularly monitored for MEN1-related tumors with imaging and laboratory tests, though the results remained negative. 8 years later, SPECT-CT was recommended for follow up of hypercalcemia with high normal i-PTH which demonstrated abnormal foci of radiotracer retention. He underwent parathyroidectomy, once again, with pathology confirming left inferior parathyroid hyperplasia. After continued recommendations for family screening of MEN1, genetic testing identified a pathogenic variant of MEN1 c.95C>G (p.Pro32Arg). Our patient demonstrates an unusual presentation of this syndrome with an initial case of lung carcinoid tumor and a 9 year history of isolated hyperparathyroidism. Conclusion:This case contributes information about the variants of MEN1 in which a Hispanic mother and son had two different presentations of the same inherited syndrome. These results point to a variant mutation in this particular case. Further genetic analysis of the patient's family may offer insights into the inheritance of MEN1 variants and whether other mutations impact its clinical presentation, thereby enhancing our understanding of related syndromes associated with MEN1. In addition, it might contribute to the knowledge of gene therapy and its potential benefits for MEN1 patients. Presentation: Sunday, July 13, 2025