There are many clinical factors that may lead to shadows on the lungs, which may be caused by the following diseases: 1) Infectious diseases in the lungs, such as pneumonia and tuberculosis, or bronchiectasis and pulmonary aspergillosis. 2) Substantial tumors in the lungs, such as lung cancer, which may cause hoarseness, cough and blood in the sputum, in addition to shadows on the lungs. 3. If the shadow on the lung occurs in children and young adults, it may also be caused by diseases such as pulmonary cysts, or some patients may be caused by congenital abnormalities in the development of the lung. Since there are more causes of shadows on the lungs, the specific causes need to be further examined by patients and combined with clinical symptoms to make a comprehensive judgment.