A Case of Metastatic Colon Cancer from Carcinosarcoma of the Uterus

We report a rare case of metastatic colon cancer from carcinosarcoma of the uterus together with a review of the literature. A 67-year-old woman was hospitalized with a complaint of melena. She underwent total hysterectomy and oophorectomy for carcinosarcoma of the uterine corpus 13 years earlier. She was treated with adjuvant chemotherapy for 6 years after surgery. The descending colon was resected under a diagnosis of colon cancer in January 2003. The specimen showed a tumor, 6cm in diameter, growing in the extramural area. HE staining showed poorly differentiated adenocarcinoma which was similar to the primary cancer component of the uterus tumor, although no atypical formation was seen in the mucosal layer. Immunohistochemical study showed cytokeratin, estrogen receptor and CA125 were positive staining, but CD34, C-kit, smooth muscle actin and vimentin were negative. Then the resected tumor in the colon was diagnosed as metastasis of carcinosarcoma from the uterus. Metastatic colon cancer is very rare. No report of colon metastasis derived from carcinosarcoma of the uterus exists to our knowledge.