The expression pattern of Β-catenin in mesothelial proliferative lesions and its diagnostic utilities

Abstract

Β-Catenin is a component of the E-cadherin-catenin cell adhesion complex. It plays an important role in the Wnt/wg pathway, which conveys critical signals for cell proliferation and transformation. The Β-catenin mutation is an important event in the progression of a number of malignancies. In this study, we evaluated the immunohistochemical (IHC) pattern of Β-catenin in a spectrum of mesothelial lesions. Sixty-five formalin-fixed, paraffin-embedded blocks from 54 serous effusions and 11 pleural biopsies were examined. These cases consisted of 33 invasive mesotheliomas, 9 early mesotheliomas (with negative radiologic finding), so-called mesotheliomas in situ, and 23 reactive mesothelial proliferations. A distinct membranous and/or submembranous staining pattern was seen in 23 cases with normal and reactive mesothelium. In contrast, reduced membranous and/or submembranous antibody staining and markedly increased ectopic cytoplasmic and nuclear staining was seen in 26 cases of 33 mesotheliomas. Seven of 9 early mesotheliomas showed increased ectopic cytoplasmic and/or nuclear stain. On the basis of our findings, identification of Β-catenin staining pattern offers a useful marker in the diagnosis of mesothelial lesions and may help identify neoplastic change. Diagn. Cytopathol. 2005;33:320–324. © 2005 Wiley-Liss, Inc.