Medullary carcinoma of the thyroid with metastasis to the pituitary gland.

A case of metastatic medullary thyroid carcinoma presenting with anterior pituitary dysfunction is reported. Initial evaluation revealed an intrasellar mass at a time when serum calcitonin and carcinoembryonic antigen levels were elevated, and histological analysis of resected tissue demonstrated the presence of metastatic medullary carcinoma of the thyroid. Immunohis-tochemical analysis confirmed the presence of calcitonin in the tumor cells.