A 51-year-old man was admitted to our hospital with right lower quadrant abdominal pain, diarrhea, and fever. We diagnosed him with squamous cell carcinoma of the ascending colon after performing a colonoscopy. The upper gastrointestinal endoscopy revealed no carcinoma of the esophagus, and computed tomography revealed no lung cancer. Therefore, squamous cell carcinoma from the ascending colon was our final diagnosis. The positron emission tomography-computed tomography identified liver and bone metastases, and the patient died a month after admission. Squamous cell carcinoma of the colon is very rare. Squamous metaplasia of an adenocarcinoma is speculated to be the occurrence mechanism. It is very difficult to treat squamous cell carcinoma of the colon because it is often discovered at a highly advanced stage.
