Villous Adenoma with Advanced Cancer of the Rectum, Clinically Accompanied with Hypopotassemia

The syndrome of severe fluid and electrolyte depletion secondary to a villous tumor in the rectum or colon is rare even in Europe and America. In Japan, only several cases have been reported in the literature. We present two cases of huge villous adenoma with advanced cancer of the rectum, clinically accompanied with hypopotassemia. The first case was an 89-year-old woman with the complaint of massive mucinous diarrhea. Blood chemical studies on admission showed hypopotassemia (K 3.1 mEq/l) and hypoproteinemia (TP 5.5 g/dl), and the rectal discharge contained high level of potassium (56 mEq/l). Barium enema and endoscopic examination revealed a large villous tumor in the rectum. The resected specimen showed a flat elevated tumor, 15×7 cm in size, which was diagnosed as a villous adenoma with advanced cancer. The second case was a 68-year-old woman with the complaint of massive mucinous diarrhea and general fatigue. Laboratory data on admission showed anemia (Hb 6.0 g/dl) and severe hypopotassemia (K 2.5 mEq/l). The electrocardiogram also reflected the electrolyte depletion. A large tumor was recognized in the rectum, and endoscopic biopsies demonstrated villous adenoma with cancer. The resected specimen showed a flat elevated tumor, 16×6 cm in size, which was diagnosed as a villous adenoma with advanced cancer. The postoperative course of both patients was uneventful, and the serum potassium levels recovered normally.