Subclinical Cushing's disease with amelioration of metabolic comorbidities after removal of pituitary tumor

A 49-year-old woman with hypertension, obesity and impaired glucose tolerance (IGT) was admitted for evaluation of pituitary incidentaloma. Although she presented no Cushingoid feature, endocrine examination of hypothalamo-pituitary-adrenal (HPA) axis showed elevated basal plasma ACTH and cortisol levels, their lack of circadian rhythm, non-suppressibility to low-dose (1 mg) dexamethasone, and responsiveness to CRH, suggesting autonomous ACTH secretion from a pituitary tumor. She underwent transsphenoidal surgery, and was diagnosed as chromophobe adenoma with positive ACTH immunoreactivity. Postoperatively, her abnormal HPA axis was resolved, along with improvement of hypertension, obesity and IGT. Thus, her metabolic comorbidities are likely due to subclinical Cushing's disease.