Primary colonic squamous cell carcinoma: a case report and review of the literature.

Colonic squamous cell carcinoma is extremely rare, with no clear pathogenesis. It usually presents as an emergency. We present the surgical management of a descending colon squamous cell carcinoma, together with a review of the available cases of colonic squamous cell carcinoma in the literature. A 69-year-old woman presented with a palpable mass and abdominal pain. She underwent ultrasound and colonoscopy, which revealed a large obstructing mass at the descending colon, the biopsies of which were not diagnostic. Unfortunately, she was readmitted with bowel obstruction and underwent extended right hemicolectomy with en-bloc excision of attached small bowel and omentum because of local mass expansion. Histopathological analysis demonstrated squamous cell carcinoma with lymph node metastases. Palliative chemotherapy followed, owing to liver and peritoneal deposits. Sixty-six cases of colonic squamous cell carcinoma have been reported in the literature. The most common location is the right colon. Most cases present at a late stage. Several theories for the pathogenesis of colonic squamous cell carcinoma have been reported; the most popular is the squamous transformation of a pluripotent stem cell.