A 97-year-old woman was admitted to our hospital complaining of malaise and frequent mucous diarrhea of two months’ duration. On physical examination, the patient showed signs of volume depletion. Laboratory tests showed renal failure and hypokalemia. A colonoscopy revealed a circumferential polypoid mass covered with clear mucous fluid in the rectum. Electrolyte depletion syndrome caused by a rectal villous adenoma was diagnosed. Surgical or endoscopic resection of the tumor was avoided considering the patient’s age and the size of the polyp. External beam radiation therapy was performed in an attempt to ameliorate the symptoms. After the therapy, the patient’s diarrhea and hypokalemia improved, and the tumor decreased in size. The present case suggests that radiotherapy is a possible therapeutic option for inoperable patients with electrolyte depletion syndrome.
