Well-differentiated glands infiltrating through the ovarian stroma. Large areas of necrosis are also present. Metastatic deposits from colon may mimic primary ovarian tumors both clinically as well as morphologically. Features favoring primary ovarian tumor include: expansile growth pattern with pushing margins, complex papillary architecture, large size, lack of surface involvement, and the presence of benign or borderline areas. Immunohistochemical profile of primary ovarian tumors: CK7+, CK20+/- focal, CEA-, CA-125+, beta-catenin usually -ve. See previous image for features favoring metastases from colonic adenocarcinomas.