It is unfortunate to have a tumor, but it is a great fortune if it is benign. For tumors, the difference between malignant and benign is a world of difference. Characteristics of benign lung tumors Among nearly 2000 cases of primary lung tumors confirmed by surgery, about 13% of them are benign tumors. Some benign tumors, whose cell differentiation and morphology are similar to normal cells, grow slowly and do not metastasize; some benign tumors are low-grade malignant tumors and have corresponding malignant clinical manifestations; some intrapulmonary lesions, although pathologically without tumor manifestations, have clinical and imaging manifestations similar to tumors and are called tumor-like changes, which are also classified as benign tumors at present. The clinical manifestations of benign tumors in the lung are obviously related to the location of the tumor and are not specific, such as chest tightness, dyspnea, asthma-like symptoms, cough, hemoptysis, etc. Most benign tumors in the peripheral lung are asymptomatic and usually found by physical examination, while benign tumors in the bronchial lumen are often symptomatic, mainly due to partial or complete obstruction of the bronchus, causing recurrent pneumonia, wheezing, hemoptysis, etc. Classification of benign tumors Benign tumors can originate from epithelial, mesothelial tissues and other abnormal tissues, and are currently classified mainly according to pathological types, see Fig. 1.Pulmonary malformation tumor: As the name suggests, pulmonary malformation tumor is a tumor-like lesion constituted by abnormal combination of normal tissues in the lung, which is now mostly considered as congenital malformation, and the key term is “normal tissue”, so it is something benign. Because it does form “tumor-like lesions,” it is called a benign tumor, and malformations are the most common benign tumors. Lung malformation tumors occur mainly in the lung parenchyma (about 90%), are slow growing, have a long course, and are generally asymptomatic. The lesions are mostly subpleural in the periphery of the lung, round or oval, lobulated, with uniform density and clear, smooth borders, some of the masses are lobulated, with multiple small nodules at the edges, some with flaky calcifications, typically in the shape of “popcorn”. The diagnosis depends mainly on imaging, but in the case of endobronchial and endotracheal malformations, pathological evidence can be obtained by fibronectomy. Pulmonary malignant tumors are rarely malignant, but it is important to make a good differential diagnosis, so the discovery of masses still requires active management, especially for middle-aged and elderly patients. 2. Inflammatory pseudotumor: Pulmonary inflammatory pseudotumor is formed by the chronicization of nonspecific inflammation and formation of mechanized pneumonia, which then confines to form a tumor-like mass, not a true tumor. It is often a single isolated lesion, spherical or oval, about 3 cm in diameter, with an envelope, and clearly decomposed from the surrounding normal tissue. It is mostly asymptomatic, often found during physical examination, and some patients may have symptoms of respiratory tract infection. It is sometimes difficult to distinguish it from lung cancer clinically. 3.Bronchial smooth muscle tumor: it is less common clinically and mostly occurs in women. If the tumor is located in the periphery of the lung, it is often asymptomatic. If it occurs in the main bronchus or lobe bronchus, cough may appear in the early stage, and if the tumor is large, it may cause narrowing of the lumen, or restricted croup may be heard. It is important to differentiate especially when secondary infection is present. Bronchial smooth muscle tumor is often not easily distinguished from lung cancer and so on, so surgery is mostly advocated, and most of them have good prognosis after surgery. Caution For small nodules in the lung with unknown etiology sometimes it is difficult to distinguish benign from malignant. Patients can be followed up closely according to whether they have cancer risk factors, such as smoking, family history of tumor, chronic lung disease, nodule diameter and density, and invasive operation or surgical intervention when necessary. Principles of management of benign lung tumors: If the pathology is confirmed as benign, and there is no clinical manifestation and no malignant tendency, the tumor can be survived with regular follow-up; once clinical symptoms and signs appear and there is malignant tendency, surgical resection should be considered. Certain benign tumors growing in the wall or lumen of trachea or bronchus can be treated by bronchoscopic laser cautery, freezing, argon knife, etc., and if necessary, resection by dissection.