Primary malignant fibrous histiocytoma of the ascending colon: report of a case.

We report a rare case of primary malignant fibrous histiocytoma (MFH) of the ascending colon. A 66-year-old man presented to our hospital with epigastralgia, and abdominal ultrasonography and computed tomography showed a large soft-tissue mass in the ascending colon. Barium enema and endoscopic examination showed a huge tumor in the ascending colon. At laparotomy, we found a tumor in the ascending colon and performed a right hemicolectomy with en bloc lymph node dissection. The resected specimen contained a tumor measuring 14.5 x 8.0 x 4.5 cm, the cut surface of which was yellowish. Based on histological and immunohistological studies, the tumor was diagnosed as MFH of the ascending colon. To our knowledge, only 20 cases of colorectal MFH, including our case, have been documented, which we review following this case report.