Clear Cell Adenocarcinoma of the Colon in the Setting of Attenuated Familial Polyposis: A Rare Variant of Primary Colonic Adenocarcinoma

Clear cell adenocarcinoma of the colon has been described rarely in the literature. It affects more commonly elderly men and usually appears in the left side of the colon. A 52-year-old male with a past medical history of attenuated FAP, who was diagnosed during a routine colonoscopy with bifocal tumor associated to 2 polyps of the transverse colon. Physical exam was normal. Laboratory data was unremarkable. A total colectomy with ileo-rectal anastomosis was performed. Gross examination of surgical specimen revealed 3 tumors and 6 pedicaulated polyps. Histopathology analysis of both coecal tumors conclude to an intestinal type adenocarcinoma. However, for the third one located in the left colon was histologically different displaying clear cell features. The later showed at immunohistochemistry study a positive staining for CK20, CDX2, while it was negative for CK 7 and CD 10. These results confirmed the clear cell variant of the adenocarcinoma. Clear cell adenocarcinomas usually arises from kidneys and Mûllerian organs. Colorectal occurrence is rare especially in the setting of attenuated adenomatous polyposis. More research and information about this malignancy is needed, especially in regard to prognosis and in order to provide the best treatment option.