Thyroid cancer, nonmedullary, 1

Nonmedullary thyroid cancer (NMTC) comprises thyroid cancers of follicular cell origin and accounts for more than 95% of all thyroid cancer cases. The remaining cancers originate from parafollicular cells (medullary thyroid cancer, MTC; 155240). NMTC is classified into 4 groups: papillary, follicular (188470), Hurthle cell (607464), and anaplastic. Approximately 5% of NMTC is hereditary, occurring as a component of a familial cancer syndrome (e.g., familial adenomatous polyposis, 175100; Carney complex, 160980) or as a primary feature (familial NMTC or FNMTC). Papillary thyroid cancer (PTC) is the most common histologic subtype of FNMTC, accounting for approximately 85% of cases (summary by Vriens et al., 2009). PTC is characterized by distinctive nuclear alterations including pseudoinclusions, grooves, and chromatin clearing. PTCs smaller than 1 cm are referred to as papillary microcarcinomas. These tumors have been identified in up to 35% of individuals at autopsy, suggesting that they may be extremely common although rarely clinically relevant. PTC can also be multifocal but is typically slow-growing with a tendency to spread to lymph nodes and usually has an excellent prognosis (summary by Bonora et al., 2010). Genetic Heterogeneity of Susceptibility to Nonmedullary Thyroid Cancer Other susceptibilities to nonmedullary thyroid cancer include NMTC2 (188470), caused by mutation in the SRGAP1 gene (606523); NMTC3 (606240), mapped to chromosome 2q21; NMTC4 (616534), caused by mutation in the FOXE1 gene (602617); and NMTC5 (616535), caused by mutation in the HABP2 gene (603924). A susceptibility locus for familial nonmedullary thyroid carcinoma with or without cell oxyphilia (TCO; 603386) has been mapped to chromosome 19p. [from OMIM]