A Case of Minute Undifferentiated Carcinoma of the Sigmoid Colon with Extensive Liver Metastases

A case of undifferentiated carcinoma of the sigmoid colon, which occurred in a pedunculated polyp and had multiple liver metastases, is reported. A 64-year-old man was admitted to Nagahori Hospital because of lower abdominal pain and melena. Barium enema and colonoscopy revealed a pedunclated polyp in the sigmoid colon. When endoscopic polypectomy was scheduled, multiple liver metastases were revealed by the echography and the computed tomography. The sigmoid colon was surgically removed and liver biopsy was performed on January 6, 1989. The resected polyp measured 10 ×8 mm. Histologically, most part of the polyp was composed of villo-tubular adenoma. In the rest medium-sized spindleshaped cancer cells were noted, which invaded the submucosa. In the liver metastases, larger polygonal cancer cells were seen. Immunohistochemically, the tumor cells were positive for neuron-specific enolase. The patient died 5 months later. Undifferentiated carcinoma of the colon is rarely reported in Japan. This is the 5th case in the literature. Even if it develops in an adenomatous polyp and is confined to the submucosal layer, colonic undifferentiated carcinoma is biologically aggresive and has a poor prognosis.