ABSTRACT
Multiple endocrine neoplasia (MEN) syndromes are autosomal dominant traits and generally characterized by the occurrence of benign and malignant tumors in two or more endocrine glands in an individual or one endocrine tumor with family history of an endocrine tumor. They are of four types. MEN 1 is characterized by commonly parathyroid, anterior pituitary, duodenopancreatic neuroendocrine tumors (NETs) and rarely foregut carcinoid and adrenal tumors. MEN 1 is caused by mutations of the MEN 1 gene, which encodes for tumor suppressor protein menin. MEN 2 (also referred to as MEN 2A) is characterized by medullary thyroid carcinoma, pheochromocytomas and parathyroid tumors. There are three variants of MEN 2-MEN 2A with Hirschsprung's disease, MEN 2A with cutaneous lichen amyloidosis and familial medullary thyroid cancer (MTC)-only. MEN3 (also referred to as MEN 2 B) is characterized by MTC and pheochromocytomas along with marfanoid habitus, mucosal neuromas, medullated corneal fibers and intestinal ganglioneuromatosis. MEN 2A and B are due to rearranged during transfection (RET) proto-oncogene mutations, which causes activation of receptor tyrosine kinase. MEN4 is caused by mutations of cyclin-dependent kinase inhibitor p27Kip1 (CDKN1B) gene and characterized by the development of parathyroid, anterior pituitary and pancreatic NETs with gonadal, adrenal, renal and thyroid tumors. Genetic testing should be offered to all diagnosed MEN patients and their first-degree relatives, and periodic clinical, biochemical and radiologic screening should be done in individuals with mutation so that tumors are detected at an early stage. The aim of treatment is cure of tumors with minimal morbidity and mortality with a good quality of life, and it requires a multidisciplinary approach.
