Nonmedullary

Nonmedullary is a medical descriptor most commonly used in thyroid oncology to denote cancers that do not arise from the parafollicular C cells, which are associated with the thyroid’s medullary component. In this context, nonmedullary thyroid carcinomas (NMTC) include the majority of thyroid cancers that originate from follicular epithelial cells, such as papillary, follicular, and Hurthle cell (oncocytic) variants, as well as poorly differentiated and anaplastic carcinomas. Medullary thyroid carcinoma (MTC), by contrast, arises from C cells and is treated and studied as a distinct entity. The classification helps clinicians and researchers distinguish tumors by cellular origin rather than solely by anatomical location.

Epidemiology and biology: Papillary thyroid carcinoma is the most common NMTC, followed by follicular carcinoma; Hurthle cell carcinomas are typically grouped with follicular-derived tumors. NMTCs tend to have favorable outcomes when detected early, especially the differentiated forms. Genetic associations differ from MTC; NMTCs are not characteristically linked to RET mutations seen in MEN2 syndromes. Instead, alterations such as BRAF, RAS, and other pathway changes are more relevant to NMTC subtypes.

Management and prognosis: Treatment generally involves surgical resection of the thyroid, with extent determined by histology and stage. Differentiated NMTCs (papillary and follicular) may be followed by radioactive iodine therapy and TSH suppression, whereas MTC is managed separately and often not with radioactive iodine. Prognosis varies by histology and stage: papillary and follicular cancers typically have good long-term survival, while poorly differentiated and anaplastic forms carry higher risk of mortality. The term nonmedullary is sometimes used less in modern practice, with explicit histological classification preferred.