[Definition] Pulmonary segregation (pulmonaryseguestration), also known as pulmonary cysticercosis with abnormal arterial blood supply, is a relatively common clinical congenital malformation of lung development, accounting for 0.15% to 6.4% of lung diseases and 1.1% to 1.8% of lung resections. It is a non-respiratory cystic mass with isolated lungs that may have their own bronchi. The former is located in the dirty pleural tissue, and its cystic lesion is connected or not connected with the normal bronchi, which is often seen clinically; the latter is covered by its own pleura, independent of the normal lung tissue, and the cystic cavity is not connected with the normal bronchi.
[Etiology].
During embryonic development, the pulmonary artery is underdeveloped so that the blood supply to a part of the lung tissue is obstructed, and a branch of the aorta replaces the pulmonary artery to supply the lung tissue in this area, and because the oxygen content of the blood from the aorta is completely different from the blood from the pulmonary artery making the lung function of this section of the lung tissue impossible, and thus underdeveloped and without lung function.
[Pathogenesis].
The mechanism of pulmonary segregation is unclear, and there are the parapneumonic bud theory, Prvce’s traction theory, and Smith’s vascular insufficiency theory. prvce’s traction theory is generally recognized, which believes that in the early embryonic prointestine and around the pulmonary bud, there are many visceral capillaries connected to the dorsal aorta, and when the lung tissue detaches, these connected vessels gradually decline and absorb. For some reason, when vascular remnants occur, they become abnormal branch arteries of the aorta and tract a portion of the embryonic lung tissue, forming pulmonary isolation disease. This part of the lung tissue is isolated from the normal bronchi and pulmonary arteries and is supplied with blood by the anomalous artery. In the early embryonic stage, when the lung tissue is tractioned during detachment from the primary intestine and the parapneumonic buds are located within the pleura, intrafollicular pulmonary segregation is formed, and after detachment, the abnormal pulmonary buds that are tractioned appear after the pleura has formed, and extralobar pulmonary segregation is formed. However, the traction doctrine does not explain all pulmonary segregation. There are a few cases of pulmonary segregation without anomalous arteries, or with anomalous arteries without segregated lungs.
In both extralobar and intralobar pulmonary isolation, the major arteries originate from branches of the body circulation, primarily the descending aorta, but also from the superior abdominal aorta, the celiac artery and its branches, the ascending main or aortic arch, the innominate artery, the subclavian artery, the internal mammary artery, the intercostal artery, the phrenic artery, or the renal artery. Most enter the isolated lung via the inferior pulmonary ligament, often in one branch, but also in two or more branches, but less commonly. The arteries vary in thickness, some up to about 1 cm in diameter The structure of the walls of these anomalous arteries is similar to that of the aorta containing more elastic fibrous tissue with higher pressure, which is highly susceptible to atherosclerosis How the vessels of the body circulation develop into the isolated lung is unclear, normally the pulmonary artery originates from the 6th germinal arch and extends its branches into the pulmonary primordium, the branches of the visceral vascular plexus that initially fed the pulmonary germ gradually degenerate, preserving only the bronchial artery.
According to accepted theories, there is abundant collateral traffic between the dorsal aorta and the visceral capillaries surrounding the pulmonary buds, and one of these collateral vessels is incompletely absorbed and degenerated, forming an abnormal artery of the body circulation to feed the isolated lung tissue. At the same time, the embryonic tissue of pulmonary isolation disease is in an abnormal site, which prevents the development of pulmonary circulation vessels. The venous reflux in pulmonary segregation is inconsistent: in intralobular pulmonary segregation, blood flows back into the inferior pulmonary veins resulting in a left-left shunt and occasionally intralobular reflux into the veins of the corporal circulation. In extralobar pulmonary segregation, blood flows back into the hemichoroidal vein, the odd vein, the inferior vena cava, the innominate vein, and the intercostal vein, and there is no shunt problem.
Clinical manifestations]
Pulmonary isolation is more common in adolescents, more males than females between the ages of 10 and 40, more intralobar than extralobar, and more left than right. Due to the different types of pulmonary isolation, the clinical manifestations of common pulmonary isolation are.
Extrapulmonary isolation disease
The ratio of male to female is about 4:1; the ratio of left to right side is about 2:1. It is located in the lower thoracic cavity between the lower lobe and the diaphragm adjacent to normal lung tissue, and can also be located in the subdiaphragm, diaphragm or mediastinum. The congenital diaphragmatic hernia is the most common, accounting for about 30% of cases. Other congenital malformations include congenital bronchial cysts, congenital esophagobronchial fistula, pulmonary dysplasia, congenital heart disease, ectopic pancreas, and organ malformations such as pericardium and colon. However, lobar lung segregation can be regarded as a paralobular lung because it has a complete pleura as if it were a separate lung lobe. Because it does not communicate with the bronchi, it is pliable and contains multiple cysts of varying sizes. Pathology: The lobe is completely covered by the pleura, and the cut surface shows spongy dark brown tissue with irregularly arranged blood vessels, usually more prominent at one end of the specimen, and microscopically shows abnormal irregular arrangement of normal lung tissue with few tracheae and often immature parenchymal tissue because it is covered by its own pleura and does not communicate with the bronchi unless it communicates with the gastrointestinal tract, with little chance of infection.
Therefore, in the absence of other obvious malformations, the lobulated pulmonary artery is simply a soft tissue mass that can survive into adulthood without symptoms. It is common in newborns and is usually asymptomatic. A small percentage of lobar ectopulmonary segregation may be detected in the newborn due to a combination of malformations on routine x-ray. It is also associated with recurrent respiratory infections, malaise, dyspnea, and even congestive heart failure in advanced stages. 60% of cases are associated with ipsilateral diaphragmatic elevation, 30% with left-sided diaphragmatic hernia, and 50% are found accidentally in the left lung during autopsy, physical examination, or examination for other diseases.
Intralobar pulmonary isolation
The incidence is low, but it is more common than the lobar pattern, and 2/3 of them are located in the posterior basal segment of the left lower lobe or right lower lobe, in the paravertebral sulcus, with the following differences from the lobar pattern: similar incidence in men and women, left to right ratio 1.5:1 to 2:1, mostly located in the inner and posterior basal segments of the lower lobe, rarely combined with other congenital malformations, most often combined with esophageal diverticula, diaphragmatic hernia and other bony heart malformations, lesion tissue without its own pleura and normal lung tissue isolation There is no obvious boundary between the abnormal and normal lung tissues, which coexist in the same lung lobe. There is one or more cystic cavities, with more parenchymal parts, and the cysts are filled with mucus.
Intralobar pulmonary isolation, especially with bronchial communication, almost all cases after a certain period of time are secondary to infection, most before the age of 10 years with recurrent pulmonary infection symptoms, fever, cough, chest pain, coughing pus sputum or even coughing pus and blood sputum, and in severe cases, systemic toxicity symptoms, similar to lung abscess symptoms infection in the cystic cavity for pus, which often with bronchial or adjacent lung tissue of airway traffic. On examination local percussion turbid sounds, hypopnea, sometimes can be heard as wet stalls only cheek-related need for spectrum coarse floating L 宥 milk milk ho vinegar pregnancy video squid captive kang gnats strange photo burin hi june title executive hydra ben 0.5-2cm, abnormal arteries mostly in the lower pulmonary ligament, through the lower pulmonary ligament to reach the lesion site, are through the (lower) pulmonary venous reflux, microscopically shows similar to dilated bronchi, occasionally tube wall cartilage plate, with respiratory epithelium.
The abnormal lung tissue is accompanied by inflammation, fibrosis or abscesses. The left lung is mostly seen in the posterior basal segment of the lower lobe in 60% of cases and in the upper lobe in 15% of cases asymptomatic. The following symptoms are mostly seen in young adults: cough, sputum, hemoptysis, recurrent lung infections and palpitations and shortness of breath. The symptoms are mostly due to the lesion and bronchial traffic. The symptoms may be temporarily relieved by anti-infective treatment, but the disease may extend for months or even years. Cysts can be single or multiple, varying in size, and the surrounding lung tissue often has pneumonia. The cystic character of the shadow can be confirmed only after the inflammation has subsided, and the size of the lesion can change greatly over time, mainly depending on the amount of gas and fluid inside. If the isolated lung is infected, the shadow pattern can change considerably within a short period of time. During expiration, gas is seen to be trapped in the isolated lung.
Congenital bronchopulmonary anterior mesenteric malformation
The term is often used to represent a malformation combined with certain bronchopulmonary lesions, but in this case it refers to pulmonary segregation with gastrointestinal traffic, most commonly the cystic lumen of the segregated lung communicating with the lower esophagus or fundus, with pathologic features consistent with intralobar or extralobar pulmonary segregation.Gede first used the term in 1968 to describe this type of pulmonary segregation before the term was adopted it was classified as extralobar anomalous lung segments most commonly in the esophagus (mostly in the lower segment). It is most commonly found in the lower segment of the esophagus, but also in the stomach. It is more common on the right side, accounting for 70% to 80% of the cases, with equal incidence in both sexes, although it can also occur in adults but is mostly diagnosed before the age of 1 year with chronic cough, recurrent pneumonia or respiratory distress, and is commonly accompanied by other malformations such as lobar pulmonary segregation and diaphragmatic hernia. Short scimitar syndrome Chassinant first described this syndrome in 1836 as a disease containing the following three malformations called short scimitar syndrome.
(i) Hypoplasia of the right lung;
(ii) Abnormal right pulmonary venous return, where the pulmonary veins converge into the right atrium and/or inferior vena cava;
(③) body artery blood supply. It is named because of the abnormal scimitar-shaped venous shadow on the chest radiograph next to the right heart margin. It has a clear familial tendency.
Pathologic somatic arterial supply: Most often, the upper middle lobe of the right lung is supplied by the pulmonary artery, while the lower lobe is supplied by one or more somatic arterial vessels, which may originate from the lower segment of the thoracic aorta and enter the lung parenchyma via the inferior pulmonary ligament, or from the abdominal aorta and cross the diaphragm into the inferior pulmonary ligament. Pulmonary tissue supplied by the corpora arteriosa may be normally ventilated or non-ventilated as in isolation, and shows pulmonary vascular hypertension.
Venous reflux abnormalities: There is usually only one right pulmonary vein, or two, which drain the whole lung or only the middle and lower lobe veins back into the inferior vena cava, creating a left-to-right shunt in this syndrome resulting in overloading of the right heart and a right lung that does not have normal physiologic function. The confluence of the anomalous pulmonary veins with the vena cava can be either supradiaphragmatic or subdiaphragmatic, with a similar incidence of both. Right lung anomalies: Hypoplasia or hypoplasia of the right lung is common and may be associated with bronchial malformations. Other anomalies: Other anomalies that may be combined with this syndrome include absent or hypoplastic pulmonary artery, right-sided heart, atrial septal defect, and horseshoe lung.
Diagnosis
Combined with clinical manifestations and X-ray chest features, B-ultrasound examination is used first and then CT, MRI or angiography is used further according to the situation.
Differentiation
Intralobar pulmonary isolation is distinguished from lung abscess and bronchiectasis, Bochdalek hernia and bronchial cysts. It is believed that aspiration lung abscess almost never occurs in the lower lobe, so cysts in the lower lobe adjacent to the diaphragm surface should be first considered as intralobar pulmonary isolation.
Treatment
Intralobar pulmonary isolation disease
Recurrent secondary infections can occur, so all of them should be treated surgically, mostly by lobectomy. Surgery should be performed after infection control, and antibiotics are routinely used. Because it is often combined with severe infection, the affected lung is often adherent to the chest wall. When separating these adhesions, attention must be paid to the anomalous arteries, which are mostly found in the pulmonary ligament and occasionally from the abdominal aorta, and improper management can cause fatal bleeding during and after surgery.
Extralobar pulmonary isolation disease
If it does not communicate with the gastrointestinal tract and is asymptomatic, it can be left untreated, but it is often surgically removed because the diagnosis cannot be clearly established. In lobar pulmonary isolation, isolated pneumonectomy is usually performed. During surgery, special attention should be paid to finding and dealing with the abnormal vessels especially when dealing with the inferior pulmonary ligament, as once the abnormal vessels are damaged and retracted into the abdominal cavity or mediastinum, it can cause hemorrhage and is more difficult to deal with.