Clear cell adenocarcinoma of the colon has been described scarcely in the literature. It affects elderly men more commonly than women and usually appears in the left side of the colon. A Hispanic 41-year-old female came to the emergency room with abdominal pain, vomiting, and distension. Physical exam revealed generalized tenderness without peritoneal signs. Laboratory data was unremarkable. A CT scan showed an apple-core lesion in the distal colon. A flexible sigmoidoscopy revealed an obstructive mass that made further evaluation impossible. Exploratory surgery revealed a hard mass obstructing the descending colon, which was resected. Histopathology analysis with immunohistochemistry staining was positive for cytokeratin 20, cytokeratin 10, CDX2, and villin, while it was negative for cytokeratin 7, RCC, vimentin, and CD31. These results confirmed the clear cell variant of the adenocarcinoma. Clear cell adenocarcinomas usually arise from the kidneys and Müllerian organs. Immunohistochemistry is crucial for establishing the origin of these neoplastic cells. A cytokeratin 20+/7？ with positive CDX2 is highly specific and sensitive for intestinal neoplastic origin. The main treatment has been surgery alone with moderately good results. More research and information about this malignancy is needed, especially in regard to prognosis and in order to provide the best treatment option. 1. Introduction Clear cell adenocarcinoma of the colon is a well-recognized but very rare subtype of colorectal cancer. Its true incidence and prevalence are unknown. Fewer than 20 cases have been reported in the English literature. We report a case and also review the current literature about this subtype of neoplasia. 2. Case Report A 41-year-old Hispanic female presented to the emergency room with abdominal pain, progressive distension, nausea and vomiting, and occasionally bloody stools for 2 months. She had an episode of melena one day prior to admission. Surgical history included a tubal ligation. She denied smoking, allergies, and medications as well as positive family history of cancer. On clinical examination, she had abdominal distension and mild generalized tenderness without peritoneal signs. The rectal examination was unremarkable. Hemoccult blood was negative. A contrast CT scan of the abdomen and pelvis revealed mild atelectasis in the lung bases, moderate distension of the gall bladder, and an apple core lesion in the distal descending colon measuring 3.4？cm long resulting in prominent dilation of the colon and small bowel proximal to this lesion. The colon distal
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