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. Like other malignant processes, metastatic medullary carcinoma of the thyroid may involve the pituitary gland and should be included in the differential diagnosis in the appropriate clinical setting.