Whether or not limited thickening of the pleura on both sides develops cannot be generalized and is related to the cause and severity of the disease. If it is caused by malignant tumor or poorly controlled tuberculosis, it may develop; pleural thickening caused by inflammation or benign tumor of pleura may not develop when the disease is controlled after removing the cause. 1. Development: when the malignant tumor metastasizes to the pleura, the unlimited growth of tumor cells and the continuous repair of fibroblasts lead to limited thickening of the pleura to continue to develop; when the tuberculosis is highly toxic and its own resistance is low, the tubercle bacillus can invade the pleura and lead to pleurisy, a large number of fibroblasts and proteins seep out from the peripheral blood vessels, and are finally deposited in the pleura, resulting in the continuous thickening of the pleura. 2. Non-development: when lung infection is serious, it can lead to pleurisy and pleural effusion, etc. Granulation tissue and fibrin repair damage will lead to thickening of pleura, but after removing the cause of the disease and controlling the infection, the exudate will be absorbed, and the pleura will not continue to thicken. After surgical treatment of benign tumors of pleura, the stimulation to pleura is reduced, and pleura will not thicken or may even return to normal. When limited thickening of pleura on both sides is found, it is suggested that patients should review the development of pleura regularly. If thickening is found and symptoms such as shortness of breath and dyspnea appear, they should go to regular hospitals in time for treatment, so that the cause of the disease can be relieved and health can be restored at an early date.