WT1 Is an Integral Component of an Antibody Panel to Distinguish Pancreaticobiliary and Some Ovarian Epithelial Neoplasms

We investigated whether a panel of antibodies including WT1 could separate pancreaticobiliary and ovarian carcinomas by staining 64 pancreaticobiliary adenocarcinomas, 41 ovarian serous carcinomas, and 12 primary ovarian mucinous neoplasms with WT1, cytokeratin (CK) 17, CK20, carcinoembryonic antigen (CEA), and CA-125. Moderate or strong intensity reactivity in more than 25% of cells was a positive result. Of the ovarian serous carcinomas, 38 (93%) were WT1 reactive and 22 (54%) WT1 positive, 9 (22%) had CK20 reactivity, and 3 (7%) were CK20 positive in fewer than 50% of cells. All were CK17 or CEA nonreactive. Of the ovarian mucinous neoplasms, all were WT1 and CK17 nonreactive and 11 (92%) were CEA reactive, 8 (67%) CEA positive, 10 (83%) CK20 reactive, and 6 (50%) CK20 positive. Of the pancreaticobiliary adenocarcinomas, 19 (30%) were CK20 positive, 27 (42%) CK17 positive, and 52 (81%) CEA positive. All were WT1 nonreactive. A panel including WT1, CK17, CK20, and CEA is useful to distinguish pancreaticobiliary and ovarian serous carcinomas. Extensive CK17 reactivity is supportive of a pancreaticobiliary adenocarcinoma when the differential diagnosis includes ovarian mucinous neoplasm. None of the antibodies positively identified ovarian mucinous neoplasms. Metastatic pancreaticobiliary adenocarcinomas and ovarian carcinomas can be morphologically, clinically, and radiographically difficult to distinguish. Both neoplasms can extensively involve the peritoneum, omentum, retroperitoneal lymph nodes, and liver. Metastatic pancreaticobiliary mucinous adenocarcinoma to the ovaries also can simulate