Pathological Approach to Pleural Malignant Mesothelioma
Exposure to asbestos can lead to asbestosis or malignancy 10-40 years after initial exposure [1]. Although its use has been banned in multiple countries, past occupational exposure leads to most cases that we see in present time. Malignant mesothelioma is an insidious and rare neoplasm that can arise from mesothelial surface cells, being Malignant Pleural Mesothelioma (MPM) the most common type. Lifetime risk of developing mesothelioma among asbestos workers can be as high as 10 percent and latency period is approximately 30-40 years since time of exposure to development of disease [2]. Annual incidence in the united states is approximately 3,300 cases per year [3]. Median overall survival of patients with advanced unresectable disease is approximately 12 months [4]. Clinical suspicion should arise in patients with previous exposure to asbestos who present with pleural thickening and/or effusion with associated respiratory symptoms. Most symptoms are nonspecific such as chest pain, dyspnea, cough and night sweats. Initial evaluation includes chest x-ray, contrast enhanced CT of the chest to find pleural abnormalities, thoracentesis and closed pleural biopsy. However, difficulties establishing diagnosis have been illustrated on studies where thoracentesis and pleural fluid cytology only yields diagnosis in 26% of cases. The diagnosis, then, is established by morphologic and immunohistochemistry findings of cytologic and surgical specimens.