Lung nodules detected on physical examination are not necessarily 100% lung cancer, but can also be benign nodules in the lungs caused by inflammation and other factors. Lung nodules are focal dense shadows of different sizes detected by imaging, which can be caused by a variety of factors. When the nodule has the “burr sign”, i.e., the edge is not smooth; >1.5cm solid nodule, or >8mm mixed ground glass nodule, we should be alerted to the possibility of malignancy. In addition, some benign factors can also lead to pulmonary nodules. Inflammatory diseases such as pneumonia and tuberculosis can also leave nodular lesions after healing. Regular observation can be used to determine whether the nodules are malignant or not. When they increase rapidly in size in a short period of time, they are usually malignant and require early surgical treatment.