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Mesothelioma are primary malignant neoplasms of the serous membranes. They usually involve the pleura and rarely the pericardium, the peritoneum and the tunica vaginalis testis. About 90% are associated with exposure to asbestos. The exposure is generally occupational, an environmental inhalation of asbestos and asbestiform fibers in areas in Turkey has been observed and presents a major health problem. This report of a patient from Anatolia with peritoneal mesothelioma after environmental exposure outlines the importance of considering this pathology in the differential diagnosis of a Turkish patient presenting with ascites.

To determine the prevalence of immunocytochemical positivities for a panel of antibodies in benign and malignant cells in effusions with known follow-up in order to use these as diagnostic markers. Besides their ability to identify malignant epithelial cells their contribution to the differential diagnosis between carcinomatoses and mesotheliomas was investigated. 101 tumour cell positive and 53 negative effusions were stained with 12 different antibodies. Results were scored semiquantitatively per cell type. Furthermore, DNA-image cytometry was performed. While prevalence of Ber-EP4 positivity was 95.4% in metastatic carcinoma cells, it was 0% in those from mesotheliomas. No cell type reacted with this marker in benign effusions (0%). Ber-EP4 correctly differentiated between metastatic carcinoma and mesothelioma in 98.0%. Prevalence of DNA-aneuploidy was 95.4% in metastatic carcinomas, 57.1% in mesotheliomas and 0% in reactive effusions. Combining immunocytochemistry (Ber-EP4 positivity) and DNA-image cytometry (aneuploidy) results in a 100% detection of metastatic carcinomatoses and 57.1% of mesotheliomas. Both markers furthermore allowed a correct differentiation of these entities in 98%.

A panel of 14 antibodies (panepithelial antibody Lu-5, anti-keratin-18, anti-keratin-7, Ber-EP4, anti-Leu-M1, HEA-125, anti-carcinoembryonic antigen, anti-blood group-related antigens A, B, H, B72.3, anti-placental alkaline phosphatase, anti-vimentin and BMA-120), which have been evaluated for use in differentiating mesothelioma from lung adenocarcinoma, was applied to a group of 24 suspected mesotheliomas. Using the established qualitative, descriptive criteria derived from monovariate statistical analysis of the tumour control groups (definite mesotheliomas, adenocarcinomas), a definitive allocation was possible in only 25% of suspected cases. We therefore constructed two "expert systems", based on multivariate discriminant analysis with either the ALLOC 80 program for ordinal data or a newly developed analysis program for binomial data. With these two systems diagnostic allocation of suspected mesotheliomas was improved to 75% and 79%. The use of binomial data ("positive" versus "negative") in conjunction with the probability-based test system is of particular interest because the primary data are easy to record and the test results have a higher statistical probability.

Specimens of 27 histologically definite mesotheliomas and 34 proven adenocarcinomas were examined with a panel of 14 antibodies: pan-epithelial antibody Lu-5, anti-keratin-18, anti-keratin-7, Ber-EP4, anti-Leu-M1, HEA-125, anti-carcino-embryonic antigen (CEA), anti-blood group-related antigens (anti-BGR A, B, H), B72.3, anti-placental alkaline phosphatase (PLAP), anti-vimentin and BMA-120 used to determine their value in the differentiation between pleural mesothelioma and lung adenocarcinoma. Lu-5, anti-cytokeratin-7 and -18, B 72.3 and PLAP reacted in a high percentage of cases with both mesothelioma and adenocarcinoma. Anti-CEA and anti-Leu-M1 did not react with any of the 27 mesotheliomas tested but showed a reaction in 75% (anti-CEA) and 66% (anti-Leu-M1) of the lung adenocarcinomas. Seventeen percent of the adenocarcinomas and 96% of the mesotheliomas showed a positive reaction with anti-vimentin. Ber-EP4 was demonstrated in all lung adenocarcinomas, but only in 2 mesotheliomas in a focal manner (7%). HEA-125 and anti-BGR A, B, H reacted with 83% (HEA-125) and 75% (anti-BGR A, B, H) of the lung adenocarcinomas. The statistical parameters, sensitivity and efficiency were estimated and a normogram for judging the diagnostic power of a single antibody for the differential diagnosis of mesothelioma versus adenocarcinoma was developed. According to this, Ber-EP4, HEA-125, anti-BGR A, B, H and anti-CEA were, in descending order, the most powerful discriminatory antibodies.

Opinions differ widely as to the value of morphometric techniques for differentiating between mesothelial cells, mesothelioma cells and metastatic adenocarcinoma cells in pleural effusions. The significance of the changes in the chromatin structure to differentiate between these three cell types was stressed by various scientific groups only qualitatively, and until now no group has used digital methods to quantify chromatin structures. The controversy about the value of morphometric methods was the reason for conducting the following study. We wanted to investigate (i) the importance of various planimetric and texture parameters as well as invariant moments as morphometric discriminators; and (ii) to set up a data structure to make possible the further diagnostic use of the multivariate morphometric analyses method for other applications. The present findings show that nuclear size and form are not the decisive factors in differentiating between reactive cells and mesothelioma cells, but pixel related texture parameters and invariant moments are. All parameter types used showed differences between reactive cells and cells of adenocarcinoma metastases. Invariant moments and shape descriptors, but not texture parameters are used to discriminate between mesothelioma cells and cells of adenocarcinoma metastases.

In the course of the last years digital image analysis has become increasingly important in the field of quantitative pathology. This may be due to the technical development of computers which have now reached a high user-friendly standard. In the present paper we present: (1) the development of a simple system for the measurement of digital image analysis; (2) the development of a general data structure applicable to various measurements and classification strategies; and (3) the analysis of the value of invariant moments (IM) as regional descriptors to distinguish mesothelial cells from mesothelioma cells in cytologic smears of pleural fluid. The results show that the invariant moments contain information concerning the geometric distribution of the grey values of the pixels as well as the staining intensity. The invariant moments present combination parameters and are therefore ideal morphometric parameters. With the invariant moments 7 out of 7 patients with mesotheliomas and 8 out of 11 control subjects could be assigned correctly in a nonparametric discriminant analysis procedure.