[Advanced poorly differentiated adenocarcinoma of the colon with micropapillary carcinoma components except specific cytokeratin expressions, report of a case].

A 53-year-old woman had a tumor in the ascending colon. CT revealed tumor invasion to the surrounding tissue and also showed multiple swollen lymph nodes, liver metastases and ascites. Colonic tumor with severe stenosis was diagnosed by colonoscopy and the obtained biopsy specimen revealed poorly differentiated adenocarcinoma. Immunohistochemically, the tumor was positive for CEA, CK7, MUC2, MUC5AC·MUC6 (spotty) and negative for CK20, CDX2, TTF-1, GCDFP-15. Cytology of ascites also showed malignant cells. Although these protein expressions were specific for not primary colonic cancer but metastasis from ovarian cancer, the case was clinically and pathologically diagnosed as poorly differentiated adenocarcinoma of the colon with peritoneal metastases composed of micropapillary carcinoma. MLH1 and MSH2 protein expressions were normal. Even though modified FOLFOX6 chemotherapy was administered, the patient rapidly worsened due to pulmonary carcinomatous lymphangiosis and died a month after diagnosis. To determine the high-risk group of metastases, it seems necessary to require the accumulation of further cases evaluated by a precise immunohistochemistrical approach.