MEN 5: The New Kid on the Block—A Comprehensive Narrative Review

In addition to the recognized types of multiple endocrine neoplasia (MEN) syndromes (MEN 1, MEN 2a, and MEN 2b), MEN 4 was described relatively recently, and there is now a proposition of a fifth variety.It has been recognized as an independent syndrome by the 5th edition of the WHO Classification of Endocrine and Neuroendocrine Tumors as well as the 5th edition of the Genetic Tumor Syndromes.Multiple endocrine neoplasia type 5 (MEN 5) is caused by a pathogenic mutation in MYC associated factor X (MAX) gene, which is a tumor suppressor gene.The endocrine manifestations include tumors of the adrenal, pituitary, parathyroid, and pancreas.The non-endocrine tumors include renal cell carcinoma, renal oncocytoma, and carcinoma of the lung.This article thoroughly reviews the available literature and tries to understand the journey of discovery of a new syndrome in endocrine surgery.