Biologic and Clinical Perspectives on Thyroid Cancer.

The transformation of endodermal-derived thyroid follicular cells or neural crest– derived thyroid C cells leads to distinct types of cancer (Fig. 1). Follicular cells give rise to two main forms of differentiated thyroid cancer: papillary thyroid carcinoma and follicular thyroid carcinoma. Poorly differentiated and anaplastic thyroid carcinomas are comparatively rare tumors that also arise from follicular cells and are associated with aggressive disease. Medullary thyroid carcinoma is the canonical C-cell tumor and has distinct biologic features.