MULTIPLE ENDOCRINE NEOPLASIA TYPE 2 MEN 2
MEN 2, also known as Sipple syndrome, is an autosomal dominant inherited cancer syndrome occurring in 1 in 300,000 live births and comprises three subtypes depending on the combination of clinical features (Schimke 1984; Zbuk and Eng 2007; Eng 2010). MEN 2A, the most common clinical subtype, is characterized by medullary thyroid carcinoma (MTC), pheochromocytoma (PC), and hyperparathyroidism (HPT). MEN 2B, the least common subtype, is similar to MEN 2A except that component neoplasias occur earlier than that in MEN 2A, clinically apparent HPT is rarely, if ever, seen, and other features such as marfanoid habitus, ganglioneuromatosis of the mucosa, and medullated corneal nerve fibers are present (Gorlin et al. 1968). Familial MTC (FMTC) is characterized by MTC only in any given family (Farndon et al. 1986). Germline mutations in the RET proto-oncogene, on 10q11.2, have been found in 95 % of all MEN 2 probands (Eng et al. 1996a, b; Kloos et al. 2009).