If it occurs in the upper lung lobes, tuberculosis infection should be suspected, and if it is a lamellar hyperdensity shadow in the lower lung, the main consideration is lung infection, which is usually called pneumonia. The clinical manifestations may include cough, sputum, chest pain, fever or even blood in the sputum. There are also patients who do not have any symptoms and have small lamellar high-density shadows in the lungs during physical examination, especially during chest CT. In this case, if there are no critical symptoms, the patient can be dynamically observed, not necessarily easily treated with antibiotic drugs, and the chest imaging is reviewed once a month or about 3 months. Sometimes this small lamellar density shadow of the lung may dissipate or there may be no change at all.