With the enhancement of people’s health awareness and the popularization of the application of high-resolution spiral CT of the chest in physical examination, the detection of pulmonary nodules is becoming more and more common, however, the nature of pulmonary nodules or masses detected by imaging is not determined. Small pulmonary nodules, its diagnosis and treatment has been a difficult clinical point and hot spot of discussion, with complex etiology, lack of specificity of clinical manifestations, difficulty in diagnosis, and easy misdiagnosis and omission. So, how should we face these pulmonary nodules? 1. Isolated, less than 5 mm GGNs are not recommended for follow-up (1) How long it takes for AAH to become malignant is still unknown, and these lesions are usually stable or asymptomatic after several years of follow-up; (2) Lung cancer CT screening studies have shown that the average multiplication time of large pure GGNs is more than 3-5 years, and it is difficult to monitor their changes; (3) The accuracy of measuring lesions less than 5 mm is limited under current technology, and there is observer variability and reproducibility Poor; (4) Conventional CT follow-up results are uncertain and come at the cost of wasted funds and excessive radiation. 2, isolated, pure GGN larger than 5 mm, CT review 3 months after discovery of lesion to clarify its changes; if still present and unchanged, annual CT follow-up for at least 3 years (1) pure GGN and some solid nodules may disappear in a short period of time; especially in women or young patients often inflammatory; (2) antibiotics are not recommended, CT-guided aspiration biopsy is recommended; (3) if the lesion is enlarged or has increased density, surgical treatment can be Surgical treatment is taken, and the procedure is recommended for thoracoscopic dehiscence, lung segment or subsegmental resection. 3, isolated partially solid GGN, especially if the solid part is larger than 5 mm, should be considered malignant when the enlargement or no change is found on 3-month review A large number of studies have shown that partially solid GGN is more likely to be malignant than pure GGN; ? According to Henschke et al, among 233 cases with positive low-dose CT screening results, the malignancy rate of partially solid GGN was 63%, and the malignancy rate of pure GGN was 18%. 4, Multiple GGN with clear boundaries less than 5 mm should be taken as a relatively conservative plan, and 2-4 years CT follow-up is recommended (1) Surgically confirmed multiple GGN less than 5 mm are often AAH; (2) The possibility of any lesion in multiple GGN less than 5 mm evolving into invasive carcinoma has not been determined, for which a conservative approach of 2nd and 4th year CT follow-up is recommended; (3) Multiple microscopic GGN should also consider other The possibility of other lesions, such as respiratory fine bronchitis in smokers, should be considered. 5. Multiple GGN with at least one lesion larger than 5 mm but without a particularly prominent lesion are recommended for 3-month CT follow-up after the first examination and long-term follow-up thereafter for at least 3 years (1) Although there are controversial reports on the malignant potential of isolated and multiple pure GGN, some studies suggest that large lesions are more likely to develop into invasive carcinoma, but a conservative long-term annual CT follow-up is still recommended, regardless of whether the patient has smoking history. 6. Multiple GGN with prominent lesions and major lesions requiring further management, with CT confirmation of persistent lesions 3 months after the first examination, suggest more aggressive management of larger lesions, especially for solid components larger than 5 mm, with thoracoscopic dehiscence or segmental lung resection recommended as the procedure, and lobectomy not recommended. (1) Genetic analysis and pathologic subtype classification confirm mostly typical multi-source primary lung cancer requiring surgical resection; (2) Major lesion definitions:1 ① partially solid, especially GGN with solid component greater than 5 mm; ② GGN greater than 10 mm, ③ with burr sign, vacuolar sign or grid sign; ④ pure GGN or partially solid nodules with changes in lesion size or density during follow-up; ⑤ non-solid nodules appear infiltrative features.