Role of PCNA in differentiating between malignant mesothelioma and mesothelial hyperplasia: Prognostic considerations

We investigated the PCNA immunoreactivity in 35 specimens of malignant mesothelioma and 20 specimens of mesothelial hyperplasia in order to evaluate the usefulness of this parameter in differentiating between these two mesothelial proliferations, and to determine whether PCNA has any prognostic significance in mesotheliomas. Eleven of the 35 investigated malignant mesotheliomas displayed up to 25% of positive cells for PCNA expression. The remaining 24 specimens showed high percentages of positive cells ranging from 26% to 95%. All specimens of reactive hyperplasia had less than 25% of PCNA positive cells. The difference between malignant mesothelioma and mesothelial hyperplasia for PCNA immunoreactivity was statistically significant (p < 0.01). A positive relationship was also found between PCNA expression level and the overall survival of those affected by malignant mesothelioma (p = 0.0032). Our results suggest an important role for PCNA in differentiating diagnosis of mesothelial proliferations. It remains unclear whether PCNA expression truly correlates with the proliferation rate of the malignant mesotheliomas and with the overall survival of patients affected by this neoplasm.