With the clinical application of high-resolution lung CT, more and more lung nodules are being detected. Pulmonary nodules plague a large number of patients who visit the clinic. Exactly what types of nodules are dangerous, those can be treated with confidence, and what are the causes of nodule formation …… This is a common question asked by almost every patient who visits the clinic with a lung nodule. Now for the lung nodules answer the following: 1, what is a lung nodule, lung CT diameter in the lung below 2m intra-pulmonary point shadow, all belong to the lung nodules; diameter of more than 2cm mass shadow, belong to the lung mass, does not belong to the lung nodules category; 1-2cm between, belong to large nodules; diameter less than 1cm belong to small nodules, diameter less than 0.5cm belong to micro-nodules; 2, the formation of lung nodules causes: Most are due to air pollution, smoking, etc. into the body, the body’s inflammatory cells and the reaction gradually formed; another small part is the sequelae of inflammation absorption in the lungs; 3, hairy glass nodules and mixed density nodules shadow need to pay great attention to the increasing lung pathological evidence, indicating that such nodules often belong to malignant nodules, that is, lung cancer; so when you find such nodules in the body, you need to pay great attention to; 4, Most of the nodules are benign in nature, especially the larger number of lung nodules, which are less likely to be malignant, and only need to be reviewed in about half a year-1 year; 5. The nodules that need to be taken seriously are the smaller number of nodules, less than 3 in number, isolated lung nodules, hairy glass nodules, and mixed density nodular shadows, which need to be taken seriously, and it is best to obtain histopathological evidence of the corresponding nodules (which is often difficult); if it is not possible to obtain pathology, it is necessary to review the lung CT dynamically, usually in 1-3 months; if the number of nodules increases and the volume increases, surgical intervention is necessary; I hope that you, through this article, can no longer be afraid of pulmonary nodules and look at them correctly.