Right Colon Clear Cell Carcinoma of Müllerian Type.

Clear cell carcinoma (CCC) is usually seen in tissues originating from the paramesonephric (Müllerian) ducts such as the kidneys, the ovaries, the cervix and the vagina. The pathogenesis has not yet been elucidated. The diagnostic hallmark is the clear cytoplasm. Primitive CCC of the colon is a very rare entity. There are two types of CCC of the colon; the intestinal type and the Müllerien type. The differential diagnosis arises mainly with secondary metastases of renal or ovarian origin. Immunohistochemistry allows retaining the primitive character. The treatment is not yet consensual. It depends on the type of tumor and its stage. The treatment is based on surgery and possibly chemotherapy. We report the case of a 75-year-old female patient who underwent surgery for a tumor of the ascending colon. Microscopic examination concluded an extensively necrotic carcinomatous growth which infiltrated all the layers of the intestinal wall and the peritoneum. The tumor was made of clusters and spans of clear cells which were separated by thin conjunctivo-vascular septa. The tumor cells were round to polygonal with a clear, optically empty, pseudo-vegetative (physaliferous) cytoplasm. Immunohistochemistry study showed a positive staining with CK7 and a negative staining with CK20, CDX2, PAX8, P63, CD10, chromogranin, and synaptophysin. We performed a Medical Literature databases (Pubmed and Google Scholar) research. Only forty-two cases were reported in English literature. The main age is 55.7 (25-89). The sex ratio is one, but female cases were younger (52 vs. 61). The rectum is the most involved site. The left colon location is more frequent than the right one. The Müllerian type was found only at the level of the left colon and rectum. There was no CCC in the right colon of Müllerien type. The case we report herein is the first right colon CCC which is positive in CK7 staining.