The causes of lung ground glass nodule 4mm mostly include pneumonia, tuberculosis, lung tumor, etc. It is recommended to take general treatment, medication, surgery and so on. 1. Pneumonia: mostly due to fungal infection, bacterial infection, mycoplasma infection, inflammatory exudation can be manifested as ground glass nodules on imaging. According to the results of drug sensitivity, follow the doctor’s instructions to apply appropriate antibiotics, common drugs are voriconazole, moxifloxacin, levofloxacin and so on. 2. Tuberculosis: caused by Mycobacterium tuberculosis infection, which can be manifested as multiple ground-glass nodules in the lungs, and requires early, regular, appropriate amount of, the whole process of, and joint application of anti-tuberculosis drugs, such as rifampicin, isoniazid, pyrazinamide, ethambutol and so on. 2. Lung tumors: the chance of cancerous transformation of lung ground-glass nodule 4mm is relatively small, but you still can’t relax your vigilance. Generally speaking, it is necessary to carry out thin-layer chest CT examination again in about 6~12 months, and if the nodule continues to grow, surgery can be considered. Pulmonary ground-glass nodule is a small nodule, usually does not cause adverse symptoms, and after active treatment, can get a good prognosis, found multiple pulmonary nodules to the hospital in time to clarify the diagnosis, symptomatic treatment.