The Diagnostic Role of Claudins in Serous Effusions

American Journal of Clinical Pathology 2007 Jun;127(6):928-37. [Link]

Lilach Kleinberg ^A1, Arild Holth ^A1, Eduard Fridman ^A2, Ignat Schwartz ^A2, Ie-Ming Shih ^A3, Ben Davidson ^A1

^A1 Pathology Clinic, Rikshospitalet-Radiumhospitalet Medical Center, University of Oslo, Oslo, Norway
^A2 Department of Pathology, Sheba Medical Center, Tel Aviv University, Tel-Hashomer, Israel
^A3 Departments of Pathology, Gynecology, and Oncology, Johns Hopkins Medical Institutions, Baltimore, MD

Abstract

We analyzed the diagnostic role of claudins in effusion cytology in 325 effusions, including 218 ovarian, 49 breast, 15 cervical or endometrial, 10 gastrointestinal, and 8 lung adenocarcinomas and 25 malignant mesotheliomas (MMs). Specimens were analyzed for claudin-1 and claudin-3 expression using immunohistochemical analysis. Ovarian and breast adenocarcinoma were further analyzed for claudin-7 expression. Claudin-1 expression was most frequent in ovarian and cervical or endometrial adenocarcinoma compared with other adenocarcinomas and MMs (P < .001). Claudin-3 expression was comparable in adenocarcinomas of different origin but was absent in MMs (P < .001). Reactive mesothelial cells rarely expressed claudins. Claudin-7 expression was higher in ovarian than in breast adenocarcinoma (P < .001). Our data suggest that expression of claudin-3 or claudin-7 is specific for adenocarcinoma and rules out the diagnosis of cells as mesothelial and that absence of claudin-1 expression excludes ovarian carcinoma as the possible origin of metastatic adenocarcinoma. Claudins may, therefore, be of diagnostic value in effusion cytology.