Primary Adenosquamous Carcinoma of Ascending Colon – A Rare Entity

Colorectal cancers (CRC) are on the rise globally with increased incidence rate 5.7/100000 cases in developing countries like India. 1 Majority (90%) of CRC are adenocarcinoma. The primary adenosquamous carcinoma (ASC) of the colon is exceedingly rare variant of adenocarcinoma with incidence of 0.025% and accounts for 0.1% of colonic epithelial malignancies. 2 The squamous differentiation accounts for its aggressiveness and poor prognosis. Here we report a rare case of primary ASC in 80year old male who presented with large bowel obstruction and peritonitis. A 80-year-old male brought to causality with history of fever, vomiting, pain in abdomen, altered sensorium since three days. The clinical examination revealed intestinal obstruction and peritonitis. Patient was immediately subjected for radiological and hematology investigations which showed signs of bowel obstruction and perforation. On emergency exploratory laparotomy, colonic perforation was identified along with an ulcer proliferative mass in ascending colon. Gross examination of right hemicolectomy revealed 9x6x3cm ulcero proliferative mass in ascending colon. The microscopic examination showed an infiltrating tumor composed of adenocarcinoma component and areas of squamous differentiation (60%) noted. Tumor was invading through muscularis propria and serosa. Final diagnosis of primary ASC was made. Colonic ASC is rare and associated with poorer prognosis. The squamous cell differentiation has greater metastatic potential than adenocarcinoma. Compared to adenocarcinoma, ASC is more likely to manifest with advanced disease and complications. Keywords: Adenosquamous, Carcinoma, Colo