Breast enlargement with prednisone treatment.

A 17-year-old boy sought endocrine advice for an unusual gynecomastia that inexplicably recurred whenever he was treated with prednisone. This began at the age of 14, when the patient was diagnosed as having Addison's disease and was first treated with prednisone. An ensuing breast enlargement caused him to stop the medication and a regression of the gynecomastia was observed. Breast enlargement reappeared each time prednisone treatment resumed. Review of this problem led to the final diagnosis of congenital adrenal hyperplasia in a teenager who was genetically female but phenotypically male.