Stereological evaluation of malignant mesothelioma versus benign pleural hyperplasia.

The differential diagnosis between malignant mesothelioma and benign pleural hyperplasia constitutes a well-known problem. In the present study we examined unbiased stereological techniques to assess the mean nuclear volume (MNV) using the point-sampled intercepts (PSI) in 37 cases of malignant mesothelioma and in 28 cases of benign pleural hyperplasia. Neither the use of different fixatives nor the histological type of malignant mesothelioma produced any significant difference on the measured nuclear volume. The differences observed between the MNV data obtained from benign pleural hyperplasia and those from any of the three types of malignant mesothelioma were found to be highly significant. All lesions with an MNV larger than 250 microns3 were found in our study to correspond to the malignant mesothelioma type, while an MNV that was smaller than 200 microns3 could only be detected in benign specimens. These observations lead us to propose the MNV measurement using PSI as an additional tool to enhance the differential diagnosis of malignant mesothelioma versus benign pleural hyperplasia.