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Figures 11 and 12: Metastatic colonic adenocarcinoma with a deceptive pattern of invasion. This tumor is composed of variably sized cysts, without destructive stromal invasion (11), lined by mucinous epithelium with marked nuclear atypia (12). It simulates a borderline ovarian mucinous tumor with intraepithelial carcinoma. This tumor was diffusely positive for cytokeratin 20 and negative for cytokeratin 7, consistent with a colonic carcinoma (stains not illustrated). Submitted by Brigitte Ronnett, MD