Endometrial Adenocarcinoma Metastatic to the Colon Masquerading as a Primary Colon Cancer

While the majority of colonic malignancies represent primary tumors, secondary tumors are not uncommon. We present a case of endometrial cancer metastatic to the colon masquerading as a primary colonic adenocarcinoma. The clinical and pathologic characteristics of each disease are discussed. To our knowledge, this is the first reported case of endometrial cancer metastasis to the colon in the absence of endometriosis. It demonstrates the importance of using immunohistochemistry to distinguish morphologically similar tumors in a patient who seemingly presents with more than one primary malignancy.