Malignant Pleural Mesothelioma: Some Aspects of Epidemiology, Differential Diagnosis and Prognosis: Histological and immunohistochemical evaluation and follow-up of mesotheliomas diagnosed from 1964 to January 1985

Abstract

64 diffuse pleural mesotheliomas diagnosed between 1964 and January 1985 at the Institute of Pathology of the University of Freiburg were analyzed. Since 1980 an increase from one case to 10 cases per year has been observed. The tumor was 3 to 4 times more frequent in men than in women. The age distribution showed a peak between the age of 50 and 60. In 26 cases evidence of exposure to asbestos was detected. In one patient radiotherapy of Hodgkin's disease may have been of etiological significance. The median survival time was 13 months. The five-year survival rate was only 4%. Histologic reevaluation was only possible in cases diagnosed after 1975. Of 43 cases thus evaluated 26 were pure mesothelial, 15 biphasic and 2 of the spindle-cell subtype. A median survival time of 23 months for pure mesothelial mesothelioma in comparison to 13 months for the biphasic mesothelioma indicated a better prognosis for pure mesothelial mesothelioma. Although no other primary tumors were detected, in 10 cases the differential diagnosis of adenocarcinoma had to be considered, and in 3 cases tumors of non-epithelial origin had to be excluded. 35 of 43 mesothelioma were CEA-negative, 38 out of 43 cytokeratin-positive, and 33 out of 43 were EMA-positive. Factor-VIII-related antigen was not demonstrated. 12 of 43 mesotheliomas showed PAS-positive staining, 29 of 43 were stained with Alcian blue. 7 of these 29 showed a positive digestion with hyaluronidase. Although CEA may not be negative in every mesothelioma, this marker seems to be a valid tool for the differential diagnosis of adenocarcinoma. In order to safeguard against a mistaken diagnosis of pleural mesothelioma, the exclusion of other tumors is always indispensable.