Spontaneous remission of hypercortisolism presumed due to asymptomatic tumor apoplexy in ACTH-producing pituitary macroadenoma.

Cushing's disease (CD) is usually caused by secretion of ACTH by a pituitary corticotroph microadenoma. Nevertheless, 7%-20% of patients present with ACTH-secreting macroadenomas. Our aim is to report a 36-year-old female patient with CD due to solid-cystic ACTH-macroadenoma followed up during 34 months. The patient presented spontaneous remission due to presumed asymptomatic tumor apoplexy. She showed typical signs and symptoms of Cushing's syndrome (CS). Initial tests were consistent with ACTH-dependent CS: elevated urinary free cortisol, abnormal serum cortisol after low dose dexamethasone suppression test, and elevated midnight salivary cortisol, associated with high plasma ACTH levels. Pituitary magnetic resonance imaging (MRI) showed a sellar mass of 1.2 x 0.8 x 0.8 cm of diameter with supra-sellar extension leading to slight chiasmatic impingement, and showing hyperintensity on T2-weighted imaging, suggesting a cystic component. She had no visual impairment. After two months, while waiting for pituitary surgery, she presented spontaneous resolution of CS. Tests were consistent with remission of hypercortisolism: normal 24-h total urinary cortisol and normal midnight salivary cortisol. Pituitary MRI showed shrinkage of the tumor with disappearance of the chiasmatic compression. She has been free from the disease for 28 months (without hypercortisolism or hypopituitarism). The hormonal and imaging data suggested that silent apoplexy of pituitary tumor led to spontaneous remission of CS. However, recurrence of CS was described in cases following pituitary apoplexy. Therefore, careful long-term follow-up is required.