PAX8 and neoplasm: Besides intestinal-type features, most of the reported tumors showed immunohistochemical positivity for gastrointestinal markers (CK20, CK7, CDX2, villin, MUC6, and/or MUC2); PAX8, ER, and PR were usually negative, focally/weakly expressed or with positivity confined in tumor components lacking IM/diff features.