ABSTRACT
<p><b>OBJECTIVE</b>To study the role of p16 gene mutation status as detected by fluorescence in-situ hybridization (FISH) and p16 protein expression as detected by immunohistochemistry in differential diagnosis of malignant mesothelioma and benign mesothelial hyperplasia.</p><p><b>METHODS</b>p16 gene mutation status and protein expression were detected by FISH and immunohistochemistry respectively in 55 cases of pleural malignant mesothelioma and 30 cases of benign mesothelial hyperplasia.</p><p><b>RESULTS</b>FISH study showed that the rate of p16 deletion in malignant mesothelioma (81.8%,45/55) was higher than that in benign mesothelial hyperplasia (3.3%,1/30). The difference was statistically significant (P<0.05). Immunohistochemical study showed that the rate of p16 protein expression in malignant mesothelioma (23.6%) was lower than that in benign mesothelial hyperplasia (76.7%). The difference was also statistically significant. The sensitivity and specificity of FISH in distinguishing between mesothelioma and reactive mesothelial hyperplasia were higher than those of immunohistochemistry.</p><p><b>CONCLUSIONS</b>In contrast to reactive mesothelial hyperplasia, p16 gene is deleted and p16 protein is not expressed in malignant mesothelioma. The sensitivity and specificity of FISH are higher than those of immunohistochemistry in the distinction.</p>