RESUMO
Cushing's disease caused by a microadenoma located near the pituitary stalk is infrequent and spontaneous remission caused by necrosis of a corticotropinoma in such location has not been reported. A 42-year-old woman with ACTH-dependent Cushing's syndrome presented on magnetic resonance imaging (MRI) a 3-mm microadenoma attached to the pituitary stalk. Treatment with ketoconazole normalized urinary free cortisol (UFC) from 433.0 to 66.0 microg/day, although it failed to reduce elevated serum androgen levels (DHEAS 4770 ng/ml). After one year, treatment was stopped and UFC rose again to 936.0 microg/day but one month later the patient presented acute headache and signs of steroid withdrawal syndrome. Endocrine evaluation showed glucocorticoid and androgen deficiency (UFC 5.0 microg/day; DHEAS < 300 ng/ml); control MRI revealed disappearance of the microadenoma. Cushingoid signs subsided and steroid replacement was initiated, proving still necessary over two years after the episode. Infarction or hemorrhage of a corticotrope adenoma could be a probable underlying mechanism although its precipitating factor is unclear. Ketoconazole withdrawal, through abrupt increase in cortisol production and/or the interruption of a hypothetical inhibitory action on cell replication followed by tumor growth and compromise of vascular supply, may be considered as possible triggering factors. To the best of our knowledge, this is the first report of spontaneous remission of Cushing's disease caused by presumed infarction of a microadenoma, unusually located in the superior rim of the pituitary, attached to the stalk.