Illustrative Case Studies of Thyroid Carcinoma and the Emerging Role of Molecular Medicine

Four clinical cases-familial papillary carcinoma of the thyroid, micropapillary carcinoma, Hürthle cell carcinoma, and medullary carcinoma-are presented that illustrate the role for emerging biotechnologies, namely, molecular medicine, to guide decision making. In each instance, the current understanding of a thyroid cancer’s biologic behavior is constrained by histological and clinical investigation of the tumor and its host. This information did not optimally determine the appropriate extent of therapy. In familial papillary thyroid carcinoma, the identification of germline mutations could lead to active screening of families to prevent disease. In papillary thyroid microcarcinoma, molecular features could identify the small number of cases that behave aggressively and therefore merit more aggressive therapy. In Hürthle cell thyroid carcinoma, molecular features could differentiate virulence among tumors with similar histology. Medullary thyroid carcinoma may present in both familial and sporadic forms, and both germline and somatic mutations have already been identified with considerable genotype-phenotype correlations. These mutations could optimize familial screening and the prediction of tumor behavior and associated clinical features, such as pheochromocytomas. These four cases will be revisited in Chapter 22, where the impact of emergent biotechnologies will be demonstrated.