Thyroid cancer of follicular cell origin in inherited tumor syndromes.

Well-differentiated thyroid cancer accounts for 95% of thyroid malignancies. In contrast to medullary thyroid carcinoma, in which about 25% are familial, only 5% of follicular cell-derived thyroid carcinomas are a component of a familial cancer syndrome. The familial follicular cell-derived tumors or nonmedullary thyroid carcinoma encompass a heterogeneous group of diseases, and are classified into 2 distinct groups: syndromic-associated tumors, occurring in syndromes in which nonmedullary thyroid carcinomas are the predominant tumor encountered, and nonsyndromic tumors, those occurring in tumor syndromes in which thyroid involvement is a minor component. The first group, syndromic-associated tumors, includes phosphase and tensin (PTEN)-hamartoma tumor syndrome/Cowden syndrome, familial adenomatous polyposis/Gardner syndrome, Carney complex type 1, Werner syndrome, and Pendred syndrome. Other syndromes, as McCune Albright syndrome, Peutz-Jeghers syndrome, and Ataxia-teleangiectasia syndrome may be associated with the development of follicular cell-derived tumors, but the link is less established than the above syndromes. The syndromic-associated tumors are the focus of this review. The second group of familial follicular cell-derived tumors syndromes or nonsyndromic tumors, in which nonmedullary thyroid carcinomas are the major findings, include pure familial papillary thyroid carcinoma, with or without oxyphilia, familial papillary thyroid carcinoma with papillary renal cell carcinoma, and familial papillary thyroid carcinoma with multinodular goiter. This review will discuss the clinical and pathological findings of the patients with familial syndrome-associated tumors: PTEN-hamartoma tumor syndrome/Cowden syndrome, familial adenomatous polyposis syndrome, Carney complex type 1, Werner syndrome, and Pendred syndrome.