Development of acromegaly during treatment of hyperprolactinemia with bromocriptine: an unusual acidophil stem cell adenoma.

We present clinical details of a patient with a 20-yr history of amennorhea, a pituitary tumor, elevated PRL levels, and initially undetectable GH. Bromocriptine failed to fully suppress PRL, and there was no tumor shrinkage. Within 7 months of starting bromocriptine treatment, the patient developed clinical and biochemical signs of acromegaly. At surgery, a stem cell adenoma was excised. The mechanisms by which bromocriptine may have resulted in the development of acromegaly in this patient are discussed.