A Case of Cushing Syndrome Caused by ACTH Producing Atypical Lung Carcinoid Tumor

Abstract

A forty-one-year-old male who was found to have lung carcinoid tumor showed clinical features of Cushing syndrome. At the age of 38 years during a regular check-up, a chest roentgenogram showed multiple nodular shadows in the bilateral lung, and he was admitted to hospital. By open lung biopsy, he was diagnosed as having malignant carcinoid or small cell carcinoma of the lung. The abnormal lung shadows did not respond to chemotherapy (CDDP + VDS). The clinical course after discharge was uneventful until the age of 41 years, when he was readmitted to our hospital because of brain metastasis. Physical examination revealed moon face and central obesity. Plasma ACTH level was high and dexamethasone suppression test showed no cortisol suppression on 8 mg dexamethasone administration. Therefore, it was thought that the patient had ACTH producing ectopic tumor which led to Cushing syndrome. We measured the molecular weight of ACTH by column chromatography and found he had a big ACTH (molecular weight about 22,000). Reexamining him clinically and histologically, we concluded that the patient had atypical carcinoid tumor in the lung which might produce ACTH causing Cushing syndrome with metastasis to the brain.