Multiple Endocrine Neoplasias Type 2

Multiple endocrine neoplasia type 2 (MEN2), also known as Sipple syndrome, is a group of rare familial cancer syndromes involving multiple endocrine organs, most commonly thyroid, adrenal glands, and parathyroid. MEN2 was first described by Sipple in 1961 when he noticed a high association of bilateral pheochromocytomas with medullary thyroid cancer (MTC). Later, various other tissue and organ involvement was reported in areas that are not classically considered endocrine tissues like gut or skin. MEN2 is an autosomal dominant condition with very high penetrance and variable expressivity. Although MEN2 is rare, recognition is very important both for patient and family member evaluation and treatment. MEN2 is further classified into two subcategories: MEN2A and MEN2B. Both types involve the thyroid and adrenal glands, but MEN2A also causes primary hyperparathyroidism (20 % to 30%). MEN2A is further categorized into the following four subtypes: Classical MEN2A. MEN2A with cutaneous lichen amyloidosis (CLA). MEN2A with Hirschsprung disease (HD). Familial medullary thyroid cancer (FMTC). In both MEN2A and MEN2B, there is an occurrence of multicentric tumor formation in all organs where RET proto-oncogene is expressed.