Lack of tumor reduction in hyperprolactinemic women with extrasellar macroadenomas treated with bromocriptine

Three patients with hyperprolactinemia and large extrasellar pituitary macroadenomas were treated with bromocriptine, 10 mg daily, for 8 weeks. In spite of correction of their amenorrhea, galactorrhea, and hyperprolactinemia, radiologic evaluation by CT scan failed to show evidence of tumor shrinkage. After surgical resection, histologic examination revealed that PRL-secreting cells comprised only a small portion of the tumor cell population in two patients and in the third patient were completely absent. These cases illustrate that large nonfunctional pituitary tumors may mimic signs and symptoms of a prolactinoma and stress the importance of adequate radiologic evaluation during medical management.