Small cell neuroendocrine carcinoma of the thymus complicated by Cushing's syndrome. Report of a 58-year-old woman with a 3-year history of hypertension.

A 58-year-old woman with a history of Cushing's syndrome for three years presented with a mediastinal mass and received the diagnosis of small cell neuroendocrine carcinoma of the thymus invading the pericardium. On immunohistochemical study, the neoplastic cells reacted with antibodies against cytokeratin, epithelial membrane antigen, neuron-specific enolase, chromogranin, synaptophysin, and ACTH. Clinicopathologic findings of this rare case of ectopic adrenocorticotropic hormone (ACTH) syndrome are discussed with a literature review.