GIANT MEDIASTINAL PARATHYROID ADENOMAS AND MULTIPLE ENDOCRINE NEOPLASIA TYPE 1: A DIAGNOSTIC CONUNDRUM.

Context: Giant parathyroid adenoma (GPA) is a rare entity that is rarer with Multiple endocrine neoplasia type 1 (MEN1) syndrome. Objectives: Describe the clinical presentation, diagnostic difficulties, and management strategy for GPA in MEN1. Methods: We searched Pubmed, SCOPUS and EMBASE for GPA in MEN1 for GPA in association with MEN1. Hereby, we describe index case of largest ever reported GPA. Results: We identified 7 cases of GPA reported till date in association with MEN1. The mean adenoma weight was 7.1 gram. The index case is largest-ever reported GPA (weight 97 gram) in MEN1 presenting with compressive symptoms and mediastinal mass. Incidentally, she was found to have hypercalcemia with increased parathyroid hormone, suggesting primary hyperparathyroidism. The possibilities of an ectopic parathyroid tumor and thymic carcinoid were considered. She also had acromegaloid features, and was found to have a sellar tumor. Subsequently, MENIN gene mutation was identified confirming MEN1 syndrome. Patient underwent trans-sternal excision of the mass weighing 97 grams and confirmed as parathyroid adenoma on histopathologic examination. Conclusion: Despite rarity of ectopic mediastinal parathyroid tumors, calcium profile should be considered as part of work-up of considering varied etiologies of anterior mediastinal mass.