Multiple endocrine neoplasia type I and Cushing's syndrome due to an aggressive ACTH producing thymic carcinoid.

Thymic carcinoid in multiple endocrine neoplasia type 1 (MEN 1) is previously reported as a non-ACTH producing tumor. The present case is a 39-year-old man with mortal outcome from thymic carcinoid and Cushing's syndrome with high plasma ACTH. The symptom was first observed at age 29 and was relieved after extended thymectomy, with reduction of ACTH level. The tumor was positive for ACTH, Grimelius silver staining and Chromogranin A. The finding of primary hyperparathyroidism, pituitary adenoma, and a novel germline nonsense mutation (W423X) established the diagnosis of MEN 1. Cushing's syndrome due to ACTH producing thymic carcinoid should be also considered as one phenotype of the MEN 1 spectrum.