Pleural epidermoid carcinoma from displaced skin following extrapleural pneumothorax in a patient exposed to asbestos

This report illustrates a rare case of primary epidermoid carcinoma of the pleura in a patient previously treated by artificial extrapleural pneumothorax for active tuberculosis. The patient had also been occupationally exposed to asbestos. Light microscopic examination showed two different lesions: laminar pleural fragments were covered by normal squamous epithelium that was similar in all respects to epidermis, whereas nodular fragments were composed of well-differentiated infiltrating carcinoma. These findings support the hypothesis that the carcinoma arose from normal epidermis seeded in the pleural cavity during multiple air refills to maintain the pneumothorax. A possible interaction between asbestos fibres and chronic inflammation might have potentiated tumour development.