Immunohistochemical staining for vimentin and keratin in malignant mesothelioma.

Because tissue culture studies have suggested that mesothelial cells might produce large amounts of vimentin, I stained eight mesotheliomas (two fixed in alcohol) for vimentin using the Gown and Vogel monoclonal antibody 43 beta E8. The two tumors that had alcohol fixed blocks were strongly positive for vimentin, whereas one of the tumors fixed only in formalin showed moderately strong staining and two others showed very weak focal positivity; the remaining tumors were negative. In the mesotheliomas that did stain, both epithelial and spindled elements gave a positive reaction. Three alcohol-fixed lung cancers and two blocks of alcohol-fixed pleura failed to stain for vimentin. By contrast, all mesotheliomas and carcinomas, whether alcohol or formalin fixed, as well as sections of pleura, were strongly positive when stained with anticytokeratin antibody 35 beta H11. I conclude that the combination of staining for vimentin and keratin might be a useful diagnostic finding in malignant mesothelioma, but that specially fixed material is required for reliable vimentin staining.