Medullary thyroid carcinoma in multiple endocrine neoplasm type II syndromes

A case of multiple endocrine neoplasm (MEN) type IIa and 2 cases of MEN type IIb are reported. The biological behavior of medullary thyroid carcinoma was more aggressive in the MEN type IIb. C-cell hyperplasia was present in the thyroid gland of the patient with a positive family history.