Synovial sarcoma and malignant mesothelioma of the pleura: Review, differential diagnosis and possible role of apoptosis

Synovial sarcoma of the pleural cavity is exceptionally rare and may be confused, both clinically and histologically, with malignant mesothelioma, with subsequent inappropriate therapy. To address this dilemma, four biphasic synovial sarcomas (BSSs) and four biphasic malignant mesotheliomas (BMMs) were studied with a panel of mucin and immunohistochemical stains to determine if they would allow one to distinguish between the two. The BMMs were all pleural-based. The BSSs were extrapleural. The mucin and immunohistochemical stains were all performed on formalin-fixed, paraffin-embedded tissue using standard techniques, with appropriate positive and negative controls. Mucin present in BSS is,…