An adult case of Cushing’s syndrome is reported. X-ray film shows a tumor mass in the right middle mediastinum. The 24 hour urinary 17-Hydroxycorticosteroid is high and is not suppreLssed by large dose dexamethasone. The patient died of infectious shock due to bronchopneumonia and colitis. Histologically no microadenoma is found in the pituitary. Basophils have Crooke’s changes. The fascicular zones of the bilateral cortices appear to have diffuse hyperplasia The thymoma is epithelial cell carcinoma. Therefore Cushing’s syndrome in this case is due to excessive ectopic ACTH. Fibrin thrombi are also found in the small blood vessels of the kidney, thymus as well as other tissues.