C cell adenoma of the human thyroid gland.

A case of C cell thyroid adenoma in a 47-year-old female patient is described. The nodule showed progression over 34 years. The adenoma cells showed histochemical and ultrastructural properties characteristic for C cells. Histologic examination revealed no atypical features of nodule cells nor infiltration of capsule by neoplastic cells. In the period of 8 years following the excision there was neither recurrence nor metastases.