Thickened lung membranes are generally referred to as pleural thickening. Pleural thickening can be seen in a variety of diseases, the common ones are pleurisy, lung cancer, silicosis, pleural mesothelioma and so on. 1. Pleurisy: Inflammatory stimuli such as tuberculous pleurisy and exudative pleurisy can lead to fibrous thickening of pleura. Especially in patients with chronic pyothorax, it is characterized by fibrous thickening of pleural dirty layer and wall layer, forming dense thick wall of abscess and limiting lung expansion. 2. Lung cancer: when the tumor cells of lung cancer invade the pleura, it can lead to pleural thickening. 3. Silicosis: Silicosis is caused by long-term inhalation of dust containing silica. In the early stage of silicosis, there is usually no pleural thickening. Pleural thickening is usually seen in the late stages of silicosis. 4. Pleural mesothelioma: pleural mesothelioma is a primary tumor of the pleura, and patients often have a large amount of bloody pleural effusion with pleural thickening. For patients with pleural thickening, they should go to the relevant departments of regular hospitals for consultation and treatment under the guidance of professional physicians to avoid delaying the condition.