Malignant mesotheliomas with osseous and cartilaginous differentiation

This report describes ten examples of diffuse pleural tumors felt to represent malignant mesotheliomas with osseous and cartilaginous differentiation. Typically, the patients involved were elderly whites who presented with chest pain, bloody pleural effusions, and diffuse and nodular pleural disease on chest roentgenograms. An asbestos-exposure history was indicated in six of the ten patients. Seven cases were malignant fibrous mesotheliomas, and three were biphasic mesotheliomas. Results of immunoperoxidase studies for cytoplasmic keratin were positive in three of six cases of malignant fibrous mesothelioma.