The diagnostic implications of variable cytokeratin expression in mesotheliomas

Immunostaining for cytokeratin has a well-established diagnostic application in distinguishing sarcomatous mesotheliomas from sarcomas based on the premise that cytokeratin expression is common in mesotheliomas but very rare in sarcomas. However, the frequency of cytokeratin detection is highly dependent on the choice of antibody. The aim of this study was to examine the distribution of simple cytokeratins and stratified cytokeratins in 45 mesotheliomas of various types and to assess the diagnostic utility of a simple cytokeratin antibody, a stratified cytokeratin antibody, and a broad spectrum cytokeratin antibody with the aim of establishing the superiority of one for routine diagnostic use. Particular attention was paid to the potential utility of these antibodies in biopsy specimens. The broad spectrum cytokeratin antibody performed better than both the simple cytokeratin antibody (paired t-test: P < 0.01) and the stratified cytokeratin antibody (P < 0.01) as a diagnostic marker of mesothelioma and should be used in preference to the other two antibodies, particularly when considering small biopsy specimens.