Malignant Mesothelioma
Cellular Classification Histologically, mesotheliomas are composed of fibrous or epithelial elements or both. The epithelial form occasionally causes confusion with peripheral anaplastic lung carcinomas or metastatic carcinomas. Attempts at diagnosis by cytology or needle biopsy of the pleura are often unsuccessful. It can be especially difficult to differentiate mesothelioma from adenocarcinoma on small tissue specimens. Thoracoscopy can be valuable in obtaining adequate tissue specimens for diagnostic purposes. Examination of the gross tumor at surgery and use of special stains or electron microscopy can often help. The special stains reported to be most useful include periodic acid-Schiff diastase, hyaluronic acid, mucicarmine, CEA, and Leu M1. Histologic appearance appears to be of prognostic value, with most clinical studies showing that epithelial mesotheliomas have a better prognosis than sarcomatous or mixed histology mesotheliomas. Stage Information Patients with sta...