Electrolyte depletion syndrome (McKittrick-Wheelock syndrome) successfully treated by endoscopic submucosal dissection.

A 66-year-old woman presented to us with malaise, anorexia and rectal mucous discharge, and her laboratory data showed severe hyponatremia, hypokalemia, hypochloremia and renal failure. Computed tomography revealed massive occupation of the rectum by a large tumor. Colonoscopy revealed a mucus-rich villous tumor in the rectum. As there were no other factors that could cause an electrolyte disorder, she was diagnosed with McKittrick-Wheelock syndrome (MWS). The current standard treatment for MWS is partial surgical colectomy. However, surgeries are invasive and postoperative complications sometimes become an issue. After confirming no signs of submucosal invasion of the tumor by magnifying chromoendoscopic examination, endoscopic submucosal dissection (ESD) was indicated. The tumor was completely removed en bloc without adverse events. The histology showed a mucosal adenocarcinoma containing a villous component, 24.5 x 17.0 cm in size. This removal dramatically improved the patient's symptoms and the electrolyte abnormalities without medication. Although several sessions of endoscopic balloon dilation were required to treat postoperative stricture, she has been symptom-free and had no recurrence for 4 years after treatment. We experienced a case of MWS treated by ESD instead of surgery. ESD should be feasible and beneficial for the treatment of MWS.