dMM are often accompanied by pleural effusion. As a result, pleural effusion cytology is still the most commonly used, the most important method. In malignant pleural mesothelial cells papillary Changcheng, nodular distribution, who was a typical "mulberry-like", with fiber-like core of the blood vessels; were also scattered single cells, or both, there is mixed. Multinucleated giant cells with malignant plasma cells and concentrated into a small peripheral vacuoles useful for the diagnosis of features. Nucleus and nucleolus slightly irregular, but the nuclear / plasma than normal. And other types of cancer cells, the size and shape vary, the size of a malignant cell to another can be several times the size of the malignant cells, the nucleolus, nuclear / plasma ratio increased. However, either of these features are non-specific, and pleural mesothelioma is built on a variety of abnormalities found on the comprehensive evaluation. dMM pleural effusion cytology positive rate low, renshaw comprehensive reports in the literature of 7% to 77%, and to make specific diagnosis of mesothelioma in the sensitivity of 4% to 63%. Therefore, if the clinical suspicion of pleural effusion dMM and cytology-negative, the inspection should be carried out in other ways, such as chest cT, percutaneous pleural biopsy, Thoracoscopy, thoracic, and so on pleural biopsy. Xue Li-fu, and other reports 〔〕 13 Thoracoscopy for the diagnosis of pleural mesothelioma rate of 100%, instead of open heart pleural biopsy.