Clinical review 44: Medullary thyroid carcinoma: recent progress.

Abstract

MTC is a neoplasm derived from the thyroid C-cell. There are two clinical types of MTC, a sporadic form which accounts for the majority of tumors and a less common hereditary variety. Four variants of hereditary MEN 2 have been identified: 1) Multiple endocrine neoplasia type 2A (MEN 2A), the most common form, has three components; medullary thyroid carcinoma, pheochromocytoma, and hyperparathyroidism. 2) MEN 2B, is characterized by MTC, pheochromocytoma, and mucosal neuromas. 3) Familial MTC may occur without other components of MEN 2A. 4) MEN 2 in association with a pruritic skin lesion located over the upper back (cutaneous lichen amyloidosis) is the rarest variant (1). Recent efforts in the field have focused on defining the disease genes for hereditary MTC, with the expectation that the sporadic form of MTC will probably share some or all of the molecular defects. A broad outline of the molecular events implicated in the development of MTC has evolved, but none of the disease genes have been identified or cloned (2).