Pulmonary isolation is a congenital developmental abnormality in which a portion of the lung tissue is separated from the normal lung and develops separately and receives blood supply from the body circulation. Based on anatomy, there are two types of intrapulmonary and extrapulmonary segregation. Nearly 2/3 of intrapulmonary segregation is located in the paraspinal groove in the posterior part of the left lower lobe, the rest is located in the corresponding part of the right lower lobe, and the upper lobe is rarely involved. The blood supply comes mainly from the descending aorta and its branches, partly from the abdominal aorta and its branches, and the veins flow back mainly into the pulmonary veins to produce shunts, individually into the inferior vena cava or odd veins. Morphologic changes in the affected lung vary depending on the degree of development of the isolated lung tissue and the degree of infection or obstruction. The abnormal lung tissue is usually well separated from the surrounding lung tissue and contains one or more cystic cavities that are filled with mucus and may have pus in combination with infection. Microscopically, the cysts resemble dilated bronchi with respiratory epithelium and occasionally cartilage, and the epithelium is usually reduced or absent in the presence of co-infection. The clinical presentation is nonspecific, mostly not symptomatic until the co-infection of the respiratory tract, showing the signs and symptoms of lower lobe pneumonia. The infection is usually septic, occasionally tuberculosis, Nucleus or Aspergillus. Extra-pulmonary segregation is less common than intrapulmonary segregation and can be combined with other congenital anomalies. 90% of extra-pulmonary segregations occur in the left hemidiaphragm and can be located between the lower lobe and the diaphragm, under the diaphragm, within the diaphragm or in the mediastinum. The blood supply is usually from the abdominal aorta and its branches, and venous return is usually via the corpora cava, inferior vena cava, odd vein, or portal venous system, producing a left-right shunt. Morphology reveals isolated lung tissue completely encapsulated within the pleural sac with numerous lymphatic channels. The cut surface is tan spongy tissue with irregularly arranged vessels, with a low number of airways, scattered cartilage and plasma mucus glands, and often immature lung tissue. Fibrosis and inflammation may also be seen in older children and adults. Because extra-pulmonary segregation is encapsulated within the pleural sac, it is rarely co-infected unless it communicates with the gastrointestinal tract. Radiographic manifestations of pulmonary isolation are mainly round, ovoid or triangular lobulated masses with uniform density. When the bronchial or gastrointestinal tracts are connected by co-infection, cysts containing air or even fluid planes are seen. It should be differentiated from pneumonia, lung abscess and lung cyst. Bronchial iodine oil angiography shows normal bronchial compression, and aortography can show abnormal branches to help the differential diagnosis. Treatment relies primarily on surgical resection. Isolated lungs are undeveloped bronchopulmonary tissue with no lung function and are isolated from normal lung tissue in adjacent lobes, mostly in the posterior basal segment of the lower lobe. If the isolated lung is within the lobe and is encompassed by the same visceral pleura, it is called intralobular pulmonary isolation, in which the cystic cavity is partially connected to the normal bronchi and partially not, and its blood flows back into the inferior pulmonary veins; if the isolated lung is outside the lobe and is not included in the same visceral pleura, it is called extralobular pulmonary isolation, in which the cystic cavity is not connected to the normal bronchi and its blood flows back into the hemichoroid, odd or inferior vena cava veins. The lobar and intralobar forms of pulmonary isolation that do not communicate with the normal bronchi are usually asymptomatic and are usually detected on routine x-ray. Intralobar pulmonary isolation with normal bronchial communication often presents with recurrent pulmonary infections, such as fever, cough, chest pain, pus and even purulent sputum. The diagnosis of pulmonary isolation should be combined with clinical manifestations and X-ray chest film features, and ultrasound examination should be used first, followed by chest CT, chest MRI or angiography examination according to the situation. For extralobar pulmonary isolation, isolated pneumonectomy can be performed, and for intralobar pulmonary isolation, lobectomy can be performed.