With the increased awareness of physical examination and the wide application of advanced medical imaging equipment such as CT and PET-CT, the detection rate of lung nodules has increased significantly compared with the previous one, and more than 90% of these patients do not have any symptoms. Lung nodules are categorized into isolated and multiple, and multiple can be seen in one or both lungs; while isolated lung nodules include benign and malignant nodules. Inflammatory granuloma is the most common among benign lesions, accounting for about 40-50%, among which tuberculoma is the most common, and others are lung misshapen tumor, bronchial adenoma, inflammatory pseudotumor, spherical pneumonia, etc.; bronchopulmonary carcinoma is the most common among malignant nodules, accounting for about 30-40%, and others are solitary metastatic tumor and others. Isolated pulmonary nodules (SPN) are single pulmonary nodules with a diameter of less than 75px, i.e., foci within the T1 period in lung cancer. Statistical data of a large number of cases show that in SPN, about 70% of nodules with a diameter of less than 5mm are benign lesions and about 30% are cancerous nodules; while about 30% of nodules with a diameter of about 50px are benign lesions and about 70% are cancerous nodules. Therefore, if you find a small nodule in your lungs, you should pay attention to its existence, but you don’t need to be alarmed. Currently, nodules with a diameter of less than 5mm can be detected in CT examination of the lungs, but because they are too small, their benign and malignant characteristics are not obvious, and it is difficult to determine their nature in combination with various examinations. When the diameter of the nodule reaches about 25px, the characteristics gradually appear, and when the diameter is about 50px, the benign and malignant characteristics become more obvious. However, even if the diameter of the lung nodule reaches 3 cm, and even if a variety of examinations such as whole-body PET-CT are performed, 5% to 10% of patients cannot correctly determine its benign or malignant nature, and the correct diagnosis can only be made with the help of invasive examinations to obtain pathology. Diagnosis of SPN: I. Imaging: CT is the preferred method for diagnosis and differential diagnosis of SPN. Pleural depression sign, spinous protuberance, lobulation sign, short burr sign, vascular concentration sign, vacuole sign, thick-walled eccentric cavity, focal frosted glass shadow, all of these are the characteristic imaging manifestations of lung cancer. If the nodule is accompanied by calcification or a ventilation sign within the mass shadow, or if the density is pale and the margins are blurred then it is more likely to be benign. If the CT value increases by 25 to 90 HU after enhancement, it is more likely to be malignant, and if the CT value increases by less than 15 or more than 90 HU, it is more likely to be benign.PET-CT can not only understand the imaging manifestations of the nodule, but also its metabolism, and it has a sensitivity of 98% for SPN larger than 25px, and a specificity of 70-90%, and if the SUV value is ≥3.0, it is more likely to be malignant. False-negative of this test is common in bronchoalveolar carcinoma and carcinoid carcinoma of lower malignancy, while false-positive is common in granulomatous disease, and the SUV value of inflammatory nodules may be higher than that of lung cancer. Second, the multiplication time of lung nodules has a greater diagnostic value, so lung nodules that are difficult to characterize should be followed up regularly. The time required to increase the diameter of a spherical lesion by 25% is often taken as the doubling time in the workup. Benign lung nodules are less than 30 days or more than 480 days. While the doubling time for malignant nodules in the lungs is 40-360 days, different types of lung cancer have different doubling times, small cell carcinoma doubling time is about 30 days, squamous carcinoma is about 90 days, large cell carcinoma is about 120 days, and adenocarcinoma is about 150-180 days. If the lung nodule increases rapidly within a short period of time (e.g. doubling within 30 days), or grows very slowly (no change for more than 16 months), it can be considered as benign. Inflammation is more likely if the mass shrinks significantly after anti-inflammatory treatment. However, even if the nodule is considered benign, it should be followed up with regular examinations. It is generally accepted that when there is no change in SPN for more than 2 years, further evaluation is not necessary. When it is difficult to diagnose the benign or malignant nature of lung nodules morphologically, short-term observation and measurement of the growth rate of the nodules will be of great help in the characterization of the nodules, especially the small nodules, even if the slow-growing tumors, there should be a change in CT scans after one month, and the fine nodules will have a change after 2 months. Third, the final diagnosis of SPN still needs invasive operation to obtain pathological diagnosis. the status of CT-guided percutaneous mass puncture in the diagnosis of SPN is quite controversial, although it is beneficial to clarify the pathological diagnosis, but there is still a certain misdiagnosis rate and leakage of diagnosis, and some scholars believe that a considerable portion of the patients with suspicious results of the puncture pathology, and believe that the fine-needle puncture may cause tumor implantation or metastasis. At present, the mainstream opinion in the industry is that, compared with CT-guided puncture, wedge resection of small lung foci (or segmental resection), the diagnostic accuracy of the former is 100%, while the latter has a false-negative effect; the former plays a role of complete treatment, while the latter only plays a diagnostic role, and there is a risk of hemothorax, pneumothorax, hemoptysis, and metastasis of the tumor implantation, so thoracoscopic minimally invasive wedge resection of small lung foci (or segmental resection) is recommended for the clinical practice. or lung segmental resection. In conclusion, the diagnosis of isolated pulmonary nodules is a worldwide medical problem. Once small nodules are found in the lungs during physical examination, further examination and analysis should be done, which requires multi-scientific collaboration and a variety of medical techniques and equipment. If malignant possibility is high, thoracoscopic minimally invasive surgical resection should be done to clarify pathological diagnosis, pathologic typing and staging. Small pulmonary nodules that have been diagnosed with lung cancer or highly suspected of lung cancer should be treated more aggressively. Treatment of SPN: Benign nodules in the lungs are the reason why it is difficult for both doctors and patients to decide whether to perform open heart surgery or not, but the preoperative diagnosis is unable to clarify the nature of the nodules, and open heart surgery has a certain amount of trauma and other factors that bring a certain amount of pressure to the patients. In recent years, the rapid development of television thoracoscopic surgery (VATS), with its minimally invasive operation, has made the resection biopsy of SPN widely carried out. However, due to the small size of SPN, some of which are located deeper in the lung parenchyma, the chance of SPN being referred to open-heart surgery due to the inability to palpate the nodule or to detect it with the naked eye can even reach 35-46%. Therefore, how to design an accurate preoperative localization method is an urgent clinical challenge. Currently, the more advanced methods mainly apply the Hook-wire system for CT-guided puncture localization (the Hook-wire hook is connected to a metal wire, the needle is inserted after CT scanning for localization, and the needle is shown to be located in the lung nodule after repeating the CT scanning, then the hook is immediately released to expand and open the lung nodule, or the nodule is located in the lung tissues around the nodule, and the distance is <5 mm, then the metal wire is cut immediately and the needle is sent to the operating room for VATS). operating room for VATS), and CT-guided micro-spring coil localization (CT-guided micro-spring coil localization, in which the tail wire of the micro-spring coil is left in the pleural surface of the dirty layer adjacent to the lesion, and the tail wire can easily be found for localization under thoracoscopy either immediately or the next day intraoperatively), which enables accurate localization of SPN in a safe and effective manner. Television thoracoscopic surgery (VATS), as a minimally invasive procedure in thoracic surgery, is advantageous for both diagnosis and treatment of SPN. Since thoracoscopy has the function of magnifying six times, the surgical field is clearer than direct vision, and minimally invasive techniques have the advantages of less surgical trauma, less pain for the patient, quicker recovery, shorter hospitalization, and fewer postoperative complications, etc. The lesion can be excised by 2-3 small 1.5-75px incisions, and can be rapidly pathologically removed at that time. The lesion can be removed in 2-3 small incisions of 1.5-75px, and rapid pathological examination can be performed at that time to clarify the pathological diagnosis. For benign lung nodules, only wedge resection or segmental resection of small lung lesions can be performed. Minimally invasive surgery removes the lesions with minimal trauma while obtaining a pathological diagnosis, especially relieving patients from the serious psychological burden and improving their quality of life. For small lung cancers, the therapeutic effect of VATS can reach the level of traditional open thoracotomy while avoiding unnecessary open thoracotomy trauma, which is highly recommended by NCCN guidelines. According to the literature, the 5-year survival rate of small lung cancer patients without lymph node metastasis is >80%, especially the smaller the primary small lung cancer, the lower the lymph node micrometastasis rate. As the tumor increases, the metastasis rate is higher, with tumor diameter at 25px and no lymph node metastasis, while the diameter reaches 75px and lymph node metastasis is at 12% for N1 and 25% for N2. Therefore, for primary small lung cancer, the standard procedure for lung cancer surgery is recommended: lobectomy with systematic lymph node dissection. In order to preserve more healthy lung tissue, some experts also advocate selective lobectomy of lung segments, especially the dorsal segment of the right lower lung and the lingual segment of the left upper lobe. Wedge resection has also been advocated to improve perioperative safety in elderly patients and those whose lung function cannot tolerate lobectomy. The specific surgical procedure can be individualized according to the patient’s condition, and then according to the postoperative pathologic typing, staging, and the results of EGFR, ALK and other genetic tests, the corresponding comprehensive treatment can be carried out, including: chemotherapy, radiotherapy, and targeted therapy. In summary, for patients with isolated small lung nodules, early and timely diagnosis of small lung cancer has become the key to improve the survival rate of patients due to the possibility of malignant lesions, and the rapid development of VATS technology has provided a better surgical pathway for patients with isolated small lung nodules. Early diagnosis and early surgical treatment of small lung cancer can definitively prolong the survival time and improve the prognosis of lung cancer patients.