Isolated lung nodules are nodules that appear as roundish shadows with a single well-defined border and are usually less than 3 centimeters in diameter. Most of the isolated lung nodules are benign lesions, but malignant lesions cannot be excluded. 1. Benign lesions: for example, caused by atypical mycobacteria, tuberculosis, parasitic infections, etc.; rheumatoid nodules and other autoimmune diseases, fibroma, malignant tumors and other benign tumors, there is no discomfort and the nodules do not get bigger, so it is enough to have a regular checkup. 2. Malignant tumors: for example, lung adenocarcinoma, small cell lung cancer, and lung metastasis from other parts of the body, such as breast cancer, can also appear as isolated nodules, which need to be further improved with relevant examinations and etiological treatment. If isolated nodules are found in lungs, it is necessary to go to the hospital for further examination in time and follow the doctor’s instruction according to the specific type of lesion after the cause is clarified, so as to avoid delaying the condition.