[Medullary cancer of the thyroid: recent data].

We briefly review recent data on the morphology and immunohistochemistry of medullary carcinomas of the thyroid (MCT). Mixed medullary and follicular carcinomas are discussed. In discriminating between familial and sporadic forms, emphasis is put on C cell hyperplasia and incipient MCTs. Attention is drawn to the possibility of occult MCTs. Histogenesis is briefly discussed in the light of the presence of SCN.