Prolactin-secreting pituitary oncocytoma with galactorrhea--amenorrhea syndrome: a histologic, ultrastructural, and immunocytochemical study.

A case is reported of a 24-year-old woman with amenorrhea and galactorrhea and markedly elevated serum prolactin levels who underwent operative resection of a pituitary adenoma. Ultrastructural examination revealed the classic features of an oncocytoma. Immunocytochemical staining was positive for prolactin. Following excision of the tumor, serum prolactin levels returned to normal and the galactorrhea became minimal. This is the first case of a pituitary oncocytoma in which secretion of prolactin was both clinically and immunocytochemically documented.