Carcinoid tumor occurring in cystic teratoma of the kidney: a case report.

Although carcinoid tumors have occurred rarely in benign teratomas of the ovary and the testis, we believe this case is the first reported of carcinoid arising in a benign cystic teratoma of the kidney. The patient was admitted to the Tagawa Hospital with a left abdominal mass and severe epigastric pain. Retrograde and intravenous pyelograms revealed marked dilatation of the left kidney; a renal tumor was diagnosed clinically. At operation, a polycystic tumor weighing 1400g was removed. Histologically, a carcinoid tumor was evident among teratoid tissues, such as columnar epithelium, cartilage, smooth muscle, and mucous secretory glands. The patient did not have a carcinoid syndrome and had an uneventful recovery.