The role of immunohistochemistry in the diagnosis of malignant mesothelioma

The immunohistochemical diagnosis of mesothelioma is perhaps one of the mos t perplexing and controversial issues in surgical pathology. A tumor that i n essence is extremely rare has managed to captivate the attention not only of pulmonologists and thoracic surgeons but also of pathologists. Througho ut its history, mesothelioma has emerged as one of the tumors that has evad ed definitive characterization; hence, the numerous attempts at trying to e stablish not only histological criteria but also histochemical, immunohisto chemical, and ultrastructural guidelines for its diagnosis. perhaps as we e nter an era of more sophisticated technology, molecular biology will have a n opportunity to make inroads into the diagnosis and characterization of th is peculiar neoplasm, Despite the many difficulties involved in the diagnos is of malignant mesothelioma, we have recently gained significant knowledge of this entity in many respects, several decades after its description. Fr om a morphological point of view, several variations of the histological ap pearances that these tumors may exhibit have been described. Traditional hi stochemistry and electron microscopy continue to play an important role in the evaluation of these neoplasms, with ultrastructural analysis in particu lar representing the most reliable technique for making this diagnosis in e quivocal cases. However, because of its speed, cost-effectiveness, and gene ral availability, immunohistochemistry has emerged as the most commonly use d procedure for the diagnosis of mesotheliomas. We herein present a review of the current status of immunohistochemical evaluation of malignant lesion s that are suspected of having a mesothelial lineage. Copyright (C) 2000 by W.B. Saunders Company.