Medullary thyroid carcinoma (MTC) is a tumor derived from the parafollicular C cells; it represents 3% to 10% of thyroid gland malignancies, but it is responsible for up to 13.4% of deaths that are caused by thyroid cancer (1). The proportion of medullary thyroid cancer to thyroid malignancies does not show a significant variation in geography, or regional iodine status. MTC may occur in sporadic (70-84%) and familial forms (16-30%), inherited as an autosomal dominant pattern of transmission (2, 3). All ages may be affected by this neoplasm, but its incidence peaks during the fourth and sixth decaded of life for the sporadic type and the second and third for the familial type (3). There is a slow increase in incidence with age and a slight female predominance among whites. Table 1 summarized the main features of the various types of MTC.
