[Case of villous tumor of the rectum presenting with severe diarrhea and electrolyte depletion syndrome].

A 83-year-old man with a 2-year history of diarrhea was admitted hospital because of increased diarrhea and general fatigue. He had severe dehydration, hyponatremia, hypokalemia and hypochloremia. Abdominal CT showed tumor and fluid in the rectum. Colonoscopy revealed large tumor with a villous structure in the rectum. Low anterior resection was performed. The histopathological diagnosis was adenocarcinoma with villous adenoma. The immunostaining of the tumor revealed positive COX-2 expression. The diarrhea and electrolyte disturbance disappeared after the resection of tumor.