Abstract
In a period of 16 years, 8 cases of pleural mesothelioma were seen in Nakano National Chest Hospital. Seven were malignant diffuse and one was benign localized mesothelioma. One patient had a history of definite occupational exposure to asbestos, one had history of probable exposure to asbestos and one patient had a history of injection of Thorotrast into the pleural cavity thirty years ago. The benign localized case had a symptom of hypoglycemic coma and after resection of this tumor that symptcm disappeared. These eight cases, were histologically classified as 1. epithelial (papillary, tubular and solid), 2. atypical epithelial, 3. mesenchymal a. benign fibromatous b. sarcomatous, 4. biphasic. In the biphasic area in this tumor we recognized transition between epithelial cells and mesenchymal cells. This observation supports the concept that mesothelial cells can differentiate into two types of cells, epithelial and mesenchymal.
