Pituitary ACTH dependency of nodular adrenal hyperplasia in Cushing's syndrome: Report of two cases and review of the literature

Cushing's syndrome due to nodular adrenal hyperplasia comprises a clinically and biochemically heterogeneous group of disorders whose pathogenesis is unclear. We describe two patients with atypical steroid dynamics and large unilateral adrenal nodules who had pituitary ACTH-dependent disease. In the differential diagnosis of Cushing's syndrome, we recommend repeated ACTH measurement and selective venous sampling—particularly in those patients with impaired dexamethasone suppressibility and abnormal findings on computerized tomography.