Mark Podberezin
University of Saskatchewan, Canada
Title: Malignant Mesothelioma and Differential Diagnosis with Reactive Mesothelial Proliferation.
Biography
Biography: Mark Podberezin
Abstract
Malignant mesothelioma (MM) is one of most lethal forms of cancer, causing about 3000 deaths per year in USA and 5000-in Europe. Asbestos exposure is one of most important causative factor, and latency period after exposure can be as long as 40 years. Being tumor of serosal membranes, it most commonly involves pleura, with minority of cases manifesting as peritoneal mesothelioma. Despite recent advances in multimodality treatment, prognosis of MM patients is dismal, and average survival is less than a year after diagnosis. Most common clinical presentation is unilateral recurring pleural hemorrhagic effusion. However, depending on histologic variant, some patients do not have pleural effusion and present with shortness of breath and increased pleural thickness. The latter is particularly true in sarcomatoid and desmoplastic variants of MM. Definitive diagnosis of MM can be done on pleural biopsy based on combination of assessment of both morphologic and immunohistochemical findings, with the recent inclusion of molecular cytogenetic findings in the diagnostic armamentarium. Most crucial and difficult task is to separate malignant process from its benign mimics. And, despite all recent advances in the diagnosis of MM, differential diagnosis between MM and reactive mesothelial proliferation remains major challenge. Importance of careful and thorough morphologic evaluation of growth pattern cannot be overestimated. Presence of invasion is unequivocal criterion of malignancy while absence of definitive invasion seen on the biopsy still cannot completely rule out MM. Therefore, other features, such as cellularity with cell distribution and growth pattern, necrosis, and cytologic atypia have to be evaluated. Recent addition of BAP-1 immunostaining, as well as molecular studies, have proven to be very helpful in differential diagnosis between MM and reactive mesothelial proliferation. Discussion of the above diagnostic aspects is main focus of current presentation.