There are many diseases that appear as ground glass nodules on CT. 5mm in diameter is not a big size, and they may be tumors, inflammation and focal fibrosis, most of which cannot be cured by themselves and need to be treated. 1. Inflammation: if it is tuberculosis, pulmonary mycobacterial infection, should actively carry out anti-tuberculosis, anti-fungal treatment, when the infection is controlled by the elimination of the pathogen nodules will also disappear. If it is the inflammation absorption stage of common pneumonia, it means that the inflammation is already in the stage of healing, and the nodular shadow on CT will disappear when it is reviewed at a later date. 2. Tumor: If it is atypical adenomatous hyperplasia, it may return to normal after the cause of disease is removed, but it may also change into lung adenocarcinoma, which needs regular observation and follow-up. If the tumor is malignant (e.g. bronchoalveolar carcinoma and adenocarcinoma), it should be surgically removed as early as possible when the tumor is small. 3. Focal fibrosis: If the fibrosis is produced by repair after previous inflammatory injury, it will not recover, but there is no need to treat it, and regular review is enough. If it is idiopathic pulmonary fibrosis, the area of pulmonary fibrosis will gradually expand, and finally affect the lung function and lead to death, you can take anti-fibrosis drugs to slow down the development of the disease or lung transplantation. It is recommended to go to a respiratory clinic to improve the examination and receive treatment under the guidance of a doctor.