If the lung nodules do not change much within two years, the possibility of malignancy is relatively small. Benign nodules are mostly solitary, with smooth edges and almost no clinical symptoms, and require no special treatment, only regular review. Nodules caused by pathogenic bacteria need to be evaluated to assess the possible causative organisms and different treatments are given according to the causative organisms, such as antibiotics for bacterial infections, anti-tuberculosis treatment for tuberculosis, and macrolide antibiotics or quinolone antibiotics for atypical pathogens. Malignant nodules that are large and do not have smooth margins can be diagnosed by bronchoscopy or lung biopsy, and require surgery, radiation therapy, chemotherapy, or targeted drug therapy.