[A case of granulomatous inflammation of the sigmoid colon caused by a fish bone that resembled cancer].

This case involved a 76-year-old man. Total colonoscopy was performed as a second examination for colorectal cancer because of positive fecal occult blood results, revealing a neoplasm with ulceration in the sigmoid colon. We suspected type-3 colorectal cancer and performed a biopsy, but the biopsy diagnosis showed only an ulcer with active inflammation. Colonoscopic re-examination in a highly advanced medical institution revealed granulomatous inflammation of the sigmoid colon caused by a fish bone, and the fish bone was removed endoscopically. Granulomatous inflammation of the colon caused by a fish bone is very rare, but sometimes needs to be differentiated from cancer. Endoscopic therapy can also be an option, depending on abdominal findings and the penetration status of the fish bone into the large intestinal wall.