Pulmonary sequestration
Introduction
Introduction to pulmonary isolation Pulmonary sequestration, also known as pulmonary cyst with abnormal arterial blood supply, refers to a rare congenital lung malformation. A part of the lung tissue that is supplied by the abnormal systemic circulation arteries forms a cystic mass. This part of the lung tissue can communicate with the bronchus. Recurrent episodes of localized infections do not cause any respiratory symptoms when they are not connected, also known as bronchopulmonary isolation. The clinical feature is the presence of abnormal arterial blood supply. The treatment of this disease is mainly to surgically remove the diseased lung tissue. basic knowledge The proportion of illness: 0.005% Susceptible people: no specific population Mode of infection: contagious Complications: pneumonia, spinal deformity
Cause
Causes of pulmonary isolation
Pulmonary artery hypoplasia (95%)
During embryonic development, pulmonary dysplasia causes a part of the lung tissue to be impeded in blood supply, and the branch of the aorta replaces the pulmonary artery to supply the lung tissue in the area. Since the blood oxygen content from the aorta is completely different from that of the blood from the pulmonary artery, The lung function of the segmental lung tissue cannot be performed, and thus it is underdeveloped without lung function.
Pathogenesis
The mechanism of pulmonary isolation is unclear. There are common para-pulmonary buddies, Prvce's traction theory and Smith's vascular dysplasia. Prvce's traction theory is widely recognized. It is believed to be around the gut and lung buds in the early embryo. Many visceral capillaries are connected to the dorsal aorta. When the lung tissue is detached, these connected blood vessels gradually decline and absorb. For some reason, when the blood vessels remain, they become the abnormal branch artery of the aorta and pull a part of the embryonic lung tissue. Forming pulmonary isolation, this part of the lung tissue is isolated from the normal bronchus and pulmonary artery, supplying blood from the abnormal artery, being pulled when the lung tissue is separated from the original intestine in the early stage of the embryo, and the accessory lung is located in the pleura. Pulmonary sequestration, abnormal lung buds that are pulled after detachment appear after the pleura has formed, and become extra-lobular lung isolation, but the traction theory does not explain all lung isolation, and there are few pulmonary isolation without abnormal arteries. , or abnormal arteries without isolated lungs, regardless of leaf type and intralobular type, the main artery of lung isolation is sourced Branch circulation.
Mainly the descending aorta, but also from the upper part of the abdominal aorta, celiac artery and its branches, ascending or aortic arch, innominate artery, subclavian artery, internal mammary artery, intercostal artery, radial artery or renal artery, etc. The lower ligament of the lung enters the isolated lung, often one or two or more, but less common, the thickness of the artery varies, and some diameters can reach about 1 cm. The structure of these abnormal arterial walls is similar to that of the aorta. It contains more elastic fibrous tissue, higher pressure, and is prone to atherosclerosis. It is unclear how the systemic circulation of blood vessels develops into the isolated lung. Under normal circumstances, the pulmonary artery originates from the sixth embryonic arch and extends its branches. The lung primordium, the branch of the visceral vascular plexus that originally provided the lung germ, gradually degenerates, leaving only the bronchial artery. According to accepted theory, there is abundant collateral traffic between the dorsal aorta and the visceral capillaries around the lung bud. The absorption and degeneration of a certain part of the blood vessel is insufficient to form an abnormal systemic circulation artery to support the isolation of the lung tissue. At the same time, the embryonic tissue of the pulmonary isolation disease is in an abnormal part, so that the pulmonary circulation blood vessels cannot be released. The venous return of pulmonary isolation is not consistent: the blood of the intra-lobular pulmonary isolation is returned to the lower pulmonary vein, resulting in left-to-left shunt, occasional intra-intra-arterial reflux to the systemic vein, and extrahepatic lung isolation into the blood. Vein, azygous vein, inferior vena cava, innominate vein, intercostal vein, etc., there is no shunt problem at this time.
Prevention
Pulmonary isolation prevention
Congenital pulmonary cysts are congenital pulmonary dysplasia, the same as other congenital diseases. After a clear diagnosis, attention should be paid to prevention of infection and active treatment.
1, early pregnancy, avoid fever and cold. Women who have had high fever in early pregnancy, even if the child does not have obvious appearance deformity, brain tissue development may be adversely affected, manifested as mental retardation, poor learning and reaction ability, this mental retardation can not be restored. Of course, fetal fever caused by high fever is also related to the sensitivity of pregnant women to high fever and other factors.
2. Avoid getting close to dogs and cats. Few people know that cats with bacteria are also a source of infectious diseases that are a great threat to fetal malformation, and cat feces are the main route of transmission of this malignant infectious disease.
3. Avoid women who wear makeup every day. The survey shows that the incidence of fetal malformations in heavy makeup is less than 1.25 times that of heavy makeup. The main adverse effects on fetal malformation are arsenic, lead, mercury and other toxic substances contained in cosmetics, which affect the normal development of the fetus. Secondly, some of the ingredients in the cosmetics are exposed to ultraviolet rays in the sun to produce teratogenic aromatic amine compounds.
4, to avoid mental stress during pregnancy. Human emotions are controlled by the central nervous system and the endocrine system. One of the endocrine corticosteroids is closely related to human mood changes. When pregnant women are emotionally stressed, adrenocortical hormone may block the fusion of a certain tissue of the embryo. If it occurs during the first 3 months of pregnancy, it will cause malformations such as cleft lip or palate.
5. Avoid drinking alcohol. Pregnant women drink alcohol, alcohol can enter the developmental embryo through the placenta, causing serious damage to the fetus. Such as a small head, very small ear and nose and a wide upper lip.
6, avoid eating mold and vegetarian food. Experts pointed out that if pregnant women eat food contaminated with mycotoxin (mildew food), mycotoxins can cause fetal chromosome breaks in the fetus through the placenta.
Complication
Pulmonary isolation complications Complications pneumonia spinal deformity
Intralobular pulmonary isolation is often associated with pneumonia. Leaf appearance often combined with other malformations, such as diaphragmatic stenosis, ventricular septal defect, venous venous drainage, pericardial cyst, funnel chest, spinal deformity, lung non-development.
Symptom
Symptoms of pulmonary isolation common symptoms unexplained fever, chest pain, repeated pneumonia
Pulmonary sequestration is more common in adolescents, aged 10 to 40 years old, more men than women, more intralobular than leaf type, more than the right side of the left side, due to different types of lung isolation, clinical manifestations are different, common lung isolation The clinical manifestations of the disease are:
1. Leaf-external pulmonary isolation : extra-lobular pulmonary isolation is less common than intra-leaf type, the ratio of male to female is about 4:1; the ratio of left and right sides is about 2:1, mostly between the lower lobe and the diaphragm of the lower thoracic cavity. Adjacent to normal lung tissue, it can also be located under the armpit, in the diaphragm or in the mediastinum. Most congenital malformations with congenital diaphragmatic hernia are most common, accounting for about 30%. Others have congenital bronchogenic cysts, congenital esophageal bronchospasm, and lung. Non-development, congenital heart disease, ectopic pancreas and pericardium, colon and other organ malformations, etc., but extra-pleural lung isolation because of a complete pleura, like a separate lung lobe, can be regarded as a secondary lung lobe, because it does not communicate with the bronchus Therefore, the texture is flexible and contains multiple cysts of different sizes. Pathology: The leaf shape is completely covered by the pleura, the cut surface is spongy, dark brown tissue, with irregularly arranged blood vessels, usually more prominent at one end of the specimen, under the microscope, the normal lung tissue is irregularly arranged abnormally, the number of trachea Rarely, parenchymal tissue is often immature, because it contains its own pleura and does not communicate with the bronchus. Unless it is connected to the digestive tract, there is little chance of infection. Therefore, if there is no other obvious deformity, the leaf shape is only one. A soft tissue mass that survives to adults without symptoms.
Common in newborns, generally more asymptomatic, more often found in routine X-ray examination, a small number of extra-lobular pulmonary isolation can be found in the neonatal period due to combined malformations, such as repeated respiratory infections can also be seen in the digestive tract , fatigue, difficulty breathing, etc., can even appear congestive heart failure in the late stage, 60% with ipsilateral sputum swelling, 30% with left sputum, 50% at autopsy, accidental findings when examining or examining other diseases, 90% Left lung.
2. Intra-lobular pulmonary isolation: the incidence is low, but more common than the leaf type, 2/3 of which is located in the basal segment of the left lower lobe or the right lower lobe. In the paravertebral sulcus, the following is different from the leaf appearance: The incidence rate of males and females is similar, the ratio of left and right sides is 1.5:1 to 2:1, mostly located in the lower lobe, posterior basal segment, rarely combined with other congenital malformations, most often combined with esophageal diverticulum, hernia and other bones, cardiac malformations, lesions The tissue has no self-pleural pleural isolation from normal lung tissue, so there is no obvious boundary between abnormal and normal lung tissue, coexisting in the same lung lobe, with one or more cystic cavities, more substantial parts, cysts filled with mucus, intralobular lung Isolation, especially in the bronchial, almost all cases are secondary to infection after a certain period of time, most of them have symptoms of repeated pulmonary infection before the age of 10, fever, cough, chest pain, cough and sputum, even cough and blood stasis, severe Symptoms of systemic poisoning may also occur, similar to the symptoms of lung abscess. The pus is in the cystic cavity during infection. It is often associated with tracheal traffic in the bronchus or adjacent lung tissue. The local percussion is dull, the breath sound is reduced, and sometimes the wetness is heard. Sound, department The patient has clubbing, and the body arteries are mostly from the lower part of the thoracic aorta or the upper part of the abdominal aorta. The diameter is 0.5~2cm. The abnormal arteries are mostly in the lower ligament of the lower lung. The lower ligament of the lung reaches the lesion and passes through the (lower) pulmonary vein. Reflux, microscopically showing similarly dilated bronchus, occasional cartilage plate in the wall, respiratory epithelium, abnormal lung tissue with inflammation, fibrosis or abscess.
More common in the left lung, 60% in the posterior basal segment of the lower lobe, rare in the upper lobe, 15% asymptomatic, mostly in the young and middle-aged symptoms: cough, cough, hemoptysis, recurrent pulmonary infection and palpitations, shortness of breath, etc. Symptoms are caused by lesions and bronchial traffic. After anti-infective treatment, the symptoms can be temporarily relieved, but the course of disease has also been delayed for several months or even years. Cysts can be single or multiple, varying in size, and there is often pneumonia in the surrounding lung tissue. At this time, the cystic characteristics of the shadow can be confirmed after the inflammation subsides. The size of the lesion can vary greatly with time, mainly depending on the internal gas. The amount of fluid, if the isolated lung is infected, its shadow shape can change greatly in a short time. When exhaling, there is gas retention in the isolated lung.
3. Congenital bronchopulmonary anterior intestinal malformation: This term is often used to refer to a malformation combined with certain bronchopulmonary lesions, but here refers to pulmonary isolation from the gastrointestinal tract, most commonly lung isolation. The cystic cavity communicates with the lower esophagus or the fundus, and its pathological features are consistent with intralobular or extralobular pulmonary isolation. Gede first described the term in 1968. Before the term was adopted, such pulmonary isolation was classified as Leaf type, abnormal lung segment is most common in the esophagus (more in the lower segment) traffic, but also the stomach, the more common on the right side, accounting for 70% to 80%, the incidence rate of men and women, although adults can also occur, but more than 1 Pre-year diagnosis, manifested as: chronic cough, recurrent pneumonia or respiratory distress, often accompanied by other malformations, such as: extra-lobular lung isolation and paralysis.
4. Short scimitar syndrome: Chassinant first described this syndrome in 1836, and the disease with the following three malformations is called the scimitar syndrome:
1 right lung hypoplasia.
2 abnormal right pulmonary venous return, pulmonary veins into the right atrium and / or inferior vena cava.
3 body arterial blood supply, because the chest radiograph has a right heart edge next to the curved knife-like abnormal vein shadow named, it has a clear family tendency. Pathological arterial blood supply: most commonly in the right lung, the middle lobe is the pulmonary artery, and the lower lobe has one or more arterial blood vessels, which may originate from the lower part of the thoracic aorta, enter the lung parenchyma through the lower lung ligament, or From the abdominal aorta, through the diaphragm into the lower lung ligament, the lung tissue of the body artery can be normally ventilated or as a noisy, and shows pulmonary vascular hypertension.
Abnormal venous return: there is only one right pulmonary vein, or two, which drains the whole lung or only the middle and lower venous blood back to the inferior vena cava, so the syndrome forms a left-to-right shunt, causing a right heart load. Heavy, but the right lung does not have normal physiological functions, the junction of abnormal pulmonary veins and vena cava can be on the sacral or sacral, the incidence of the two is similar, right lung abnormalities: common right lung hypoplasia or dysplasia, can be associated with bronchus deformity. Other abnormalities: Other malformations that may be associated with this syndrome include pulmonary artery loss or dysplasia, right heart, atrial septal defect, and horseshoe lung. Combined with clinical manifestations, X-ray chest radiographs, first use B-ultrasound, and then further use CT, MRI or angiography according to the situation.
Examine
Pulmonary isolation test
1. X-ray chest X-ray : chest X-ray film of extra- lobular lung isolation often shows uniform, triangular, tip pointing to the shadow of the hilar, difficult to diagnose before surgery, often open chest exploration with intracranial mass diagnosis, leaf inside Type of pulmonary isolation on the chest X-ray film, see the inner and posterior basal segments of the lower lobe close to the crotch surface with a uniform density of darkening shadows, mostly round, oval, a few can be triangular or polygonal, the boundary is generally Clear, with its long axis pointing to the rear, suggesting that it is associated with the descending aorta. If the infection is combined with the bronchus, it appears as a single or multiple circle-shaped shadow with a flattening, similar to the image of the lung cyst, and the thickness of the cyst wall varies. There are inflammation images around, the size of the shadow can change with the course of the disease, the infection increases, the inflammation shrinks after absorption, but it will never disappear completely.
2. Tomography : The lesions in the posterior segment of the lower lobe sometimes overlap with the spine or heart shadow on the chest flat. The tomography clearly shows the shape, contour and internal structure of the lesion. The lesion is round, oval or triangular. The boundary is clear and can be changed in cystic size. Sometimes abnormal vascular images are connected to the aortic shadow on the body slice, showing a comma-like or cord-like shadow. The tail of the comma represents the direction of the abnormal artery. It has diagnostic significance, but abnormal blood vessels with a diameter of 0.5 cm or less are not easy to find.
3. Bronchography : The bronchus in the lesion is not developed in most cases, only the larger bronchus can be developed, and the infection may cause infection after angiography. Bronchoscopy and bronchography are meaningless.
4. Angiography: Clinically highly suspected pulmonary isolation and X-ray chest and body slices can not be determined, aortic angiography or selective angiography, can be observed in the abnormal body branch to supply the lung tissue of the lesion to be clearly diagnosed, Transfemoral catheterization, contrast agent contrast at the beginning of the descending aorta can show that abnormal blood vessels are generally from the descending aortic segment of the diaphragm, 0.5 ~ 1cm in diameter, venous return to the pulmonary vein or azygous vein, inferior vena cava However, because the abnormal blood vessels are relatively thin, the contrast dose is small, and in most cases, the venous return can not be displayed. The selective angiography technique is required to be high. The C-shaped or right-angled catheter with special angle is fed through the femoral artery puncture. The aortic diaphragm is located above and below the abnormal blood vessel. When the catheter tip is inserted into the blood vessel mouth, a contrast agent is injected. The diameter of the blood vessel is observed, and the venous return can be observed by continuously injecting the contrast agent. However, this test is a traumatic examination and has certain It is dangerous and requires certain conditions and equipment.
5. CT examination : the shape of the lesion can be clearly displayed, and the presence of abnormal arteries can be confirmed. The typical manifestations are: normal pulmonary bronchial artery and vein bundle are away from or surrounded by the periphery of the isolated lung, occasionally calcification, such as traffic with bronchial tree Infection, its manifestations include balloon swelling, with or without fluid level, inflammatory infiltration around, or cyst-like manifestations, may have gas-liquid level, but the diagnostic positive rate is not high.
6. Magnetic Resonance (MRI) : It can detect the mass of the intrathoracic boundary and its internal structure. It can be clearly shown in each section, especially the cross section. The intralobular feature is an abnormal mass in the lung (on MRI The blackened shadow is connected to the abnormal blood vessel. The leaf shape is a mass shadow that is abnormally whitened outside the lung. It is also connected with abnormal blood vessels. Magnetic resonance can see abnormal lung tissue and its relationship with surrounding organs, showing abnormality. Arterial origin, running and venous return, the results of the examination are similar to angiography, and it is a non-invasive examination method, which can replace angiography, but the examination cost is higher.
7.B-ultrasound : It can detect the round or elliptical lung mass with clear boundary and regular shape. The cystic area with different sizes can be seen inside. If there is infection, there will be scattered small light spot reflection. 0.5 around the mass. One or two blood vessels ranging from ~0.8cm enter the mass, and their imaging features are different from those of other intrapulmonary lesions. B-ultrasound is a non-invasive examination method with simple operation, high accuracy and repeated dynamic observation, but B-ultrasound can not Differentiating intralobular or extralobular pulmonary isolation, and not detecting pulmonary venous return.
Diagnosis
Diagnosis and diagnosis of pulmonary isolation
Intra-lobe pulmonary isolation and lung abscess and bronchiectasis, Bochdalek and bronchogenic cysts are identified. Some people think that inhaled lung abscess almost never occurs in the lower lobe, so the cyst in the lower lobe should be considered as the intra-leaf type. Lung isolation.
Lung abscess is a suppurative inflammation of the lung tissue caused by various pathogen infections, leading to tissue necrosis, destruction, and liquefaction to form an abscess. High fever, cough, and coughing a large number of pus sputum as the main clinical features. Common pathogens include Staphylococcus aureus, Streptococcus pyogenes, Klebsiella pneumoniae, and Pseudomonas aeruginosa.
Bronchiectasis refers to the destruction of the proximal and middle bronchial tubes due to the destruction of the muscles and elastic components of the wall, resulting in abnormal, irreversible expansion and deformation of the lumen.
