Cushing's disease due to female gonadotroph adenoma of the pituitary.

A 39-year-old woman presented with amenorrhoea, hyperprolactinaemia and sellar mass. Bromocriptine normalized PRL levels but failed to suppress tumour growth. Subsequently, she developed clinical signs and elevated blood cortisol levels consistent with a diagnosis of Cushing's disease. A pituitary tumour was removed which was immunoreactive for ACTH. Electron microscopic examination, however, revealed a female gonadotroph adenoma indicating that adenoma cells regarded as gonadotrophs by ultrastructural analysis may occasionally secrete ACTH and cause Cushing's disease.