Claudin-18 and MUC5AC Immunohistochemistry Is Useful for Distinction between Primary Ovarian Mucinous Adenocarcinoma and Metastatic Colorectal Carcinoma Involving the Ovary
Sultan Ahmad Halimi, Daichi Maeda, Masashi Fukayama. Graduate School of Medicine, University of Tokyo, Tokyo, Japan
Background: Among ovarian epithelial carcinomas, mucinous adenocarcinomas pose the greatest difficulty in terms of differentiation between primary and metastatic disease. Distinguishing these two lesions is often challenging, not only at the time of intraoperative assessment when requested for surgical management, but also at the time of final pathological diagnosis. The current study was undertaken to investigate the expression of claudin-18 (CLDN18, a tight-junction protein specifically expressed in the gastric epithelium) in both primary ovarian intestinal type mucinous adenocarcinoma (IMCa) and metastatic colorectal carcinoma (CRC) involving the ovary. We also investigated the expression of CK7, CK20, CDX2, MUC2, MUC5AC, and ER to identify a panel of markers useful for differential diagnosis between primary ovarian IMCa and metastatic cancer of colorectal origin.
Design: A total of 33 cases of ovarian adenocarcinoma, including primary IMCa (n = 17) and metastatic CRC (n = 16), were retrieved from the archive of the Department of Pathology of the University of Tokyo Hospital. Tumors were classified based on a review of hematoxylin and eosin–stained slides. A representative whole-tissue section was selected in all cases, and immunohistochemistry for CLDN18, MUC2, MUC5AC, CK7, CK20, CDX2, and ER was performed. Immunohistochemical staining was performed according to standard techniques on a Ventana Benchmark XT autostainer (Ventana Medical Systems Inc., Tucson, AZ).
Results: CLDN18, MUC5AC, and CK7 were expressed specifically in primary ovarian IMCa. Metastatic CRCs, in contrast, were almost always negative for these markers. Expression of CDX2, MUC2, and CK20 was more frequently detected in metastatic CRC than in primary IMCa. Both primary IMCa and metastatic CRC were almost always negative for ER.
|Primary IMCa||Metastatic CRC||P|
|CK7||17/17 (100%)||0/16 (0%)||<0.0001|
|CK20||9/17 (53%)||14/16 (87%)||0.057|
|CDX2||10/17 (59%)||16/16 (100%)||0.0072|
|MUC2||2/17 (12%)||9/16 (56%)||0.0104|
|MUC5AC||10/17 (59%)||0/16 (0%)||0.0003|
|CLDN18||14/17 (82%)||1/16 (6%)||<0.0001|