[A Case of Multiple Hepatic Metastases after Surgery for Low Differentiated Mucous Cancer of Sigmoid Colon with Notable Mesenteric Infiltration in Which Chemotherapy Was Effective].

Mucinous adenocarcinoma of the colon occasionally develops from the submucosa, depending on the pattern of onset; therefore, in many cases, it is already advanced at the time of diagnosis. This type of cancer is known to have a poor prognosis. We report the case of a 59-year-old woman who presented with abdominal pain on defecation for 1 month. A mass was palpable in the lower part of her abdomen. On computed tomography(CT), an extrinsic mass was seen in the sigmoid colon, and lower gastrointestinal endoscopy findings suggested an invasive tumor originating from another organ outside the intestinal wall. A high level of the tumor marker CEA(40.8 ng/mL)was observed. No findings suggestive of malignancy were present on biopsy examination, Colorectal cancer was suspected, for which a sigmoidectomy was performed. On histopathological examination, though there was little to indicate a primary colon tumor on HE staining, due to strong CDX2 positivity it was suspected to be an intestinal-type adenocarcinoma. The final clinical diagnosis was unclassifiable, poorly differentiated, mucinous adenocarcinoma of the colon. Multiple liver metastases appeared 4 months postoperatively, which were treated with XELOX plus BV and FOLFIRI plus BV. CT evaluation 24 months postoperatively showed a complete response radiographically. This case of mucinous adenocarcinoma of the colon, in which chemotherapy was successful and long-term survival of 5 years and 2 months was achieved postoperatively, is reported together with a discussion of the literature.