Rare case of advanced rectal cancer with multiple liver and bone metastases presenting with McKittrick-Wheelock syndrome.

McKittrick-Wheelock syndrome (MWS) is a rare entity that has been described as electrolyte and fluid depletion secondary to secretory diarrhea caused by a large villous tumor in the colon or rectum. Most tumors associated with MWS are large but benign villous adenomas. Advanced cancers are seldom reported. We report a rare case of advanced rectal cancer with multiple liver and bone metastases presenting with MWS. A 59-year-old man was admitted to our hospital with a more than 3-year history of chronic mucous diarrhea. Laboratory data revealed hyponatremia, hypokalemia, hypochloremia, and renal failure. Based on the findings on colonoscopy, computed tomography, and magnetic resonance imaging, he was diagnosed with advanced rectal cancer with liver and bone metastases, and MWS. Following intravenous fluid treatment, abdominoperineal resection of the rectum with lymph node dissection was performed. The surgically resected specimen was a circumferential villous tumor measuring 110 × 80 mm. Histological examination of the resected specimens revealed signet ring cell carcinoma with villous adenoma and metastasis in regional lymph nodes. The renal dysfunction and electrolyte abnormalities that were present before surgery improved. Two courses of capecitabine were administered as adjuvant chemotherapy after the surgery. However, approximately 2 months after surgery, he died of poor general condition due to progression of the liver metastases.