McLeod syndrome is a chronic pathology with progressive hypoplasia and a decrease in the density of one lung or its lobe, reduction of arterioles, obliteration of small bronchi and bullous alveolar change. The course of McLeod syndrome is accompanied by increasing expiratory dyspnea, persistent cough with intermittent scanty sputum, diffuse chest pain, chest asymmetry, respiratory failure. Diagnosis of McLeod syndrome includes radiography and CT of the lungs, bronchography, lung scintigraphy, FER examination. To eliminate the pathological symptom complex, lobectomy or pneumonectomy is performed.
J43.0 McLeod syndrome
McLeod syndrome (Swire-James syndrome, Janus syndrome, “super-transparent” lung, unilateral pulmonary emphysema) is a clinical and radiological syndrome accompanied by a decrease and progressive emphysematous changes in the lobe or entire lung, damage to the pulmonary arterioles and bronchioles. In 1953, the syndrome was described by Swyer and James; in 1954, the British pulmonologist Macleod drew in detail the pathogenesis of the disease, and the French radiologist Janus presented the radiological signs of the anomaly. McLeod syndrome is considered a relatively rare pathology (as of 1966 it was known about 100 cases of the disease), more often detected in male patients. According to the complex of manifestations, McLeod syndrome is included in the group of chronic obstructive pulmonary diseases (COPD). The study of this pathology is in the field of interests of pulmonology.
Causes of McLeod syndrome
The formation of McLeod syndrome is caused by bronchopulmonary diseases repeatedly suffered in early childhood (in the first 8 years of life), recurrent severe bronchitis and pneumonia, complicated by postinfectious obliterating bronchiolitis. The most dangerous in terms of the outcome of McLeod syndrome are bronchiolitis caused by RSV, CMV, adenovirus, influenza virus, parainfluenza, mycoplasma, legionella, pneumocystis. The secondary infection that has accumulated at the same time provokes the development of bronchiectasis.
Postinfectious bronchiolitis in early childhood occurs against the background of intensive development of alveoli from embryonic terminal and respiratory bronchioles, which contributes to the disruption of the formation of lung parenchyma.
In MacLeod syndrome, damage to the bronchiolar walls is histologically determined, including glandular hypertrophy, necrobiosis of the mucous epithelium, proliferation of granulations and submucosal layer with the formation of micropolypes, as well as peribronchial fibrosis; ruptures of the alveolar septa, thickening of the walls of the branches of the pulmonary artery and reduction of the capillary network. Sometimes there may be a picture of panacinar emphysema with separate subpleural bulls, obstruction of arterioles, expansion of small bronchi with hypoplasia of their walls. Collateral ventilation through intact respiratory tract and air intake through the pores of the Cone helps to keep the lung airy.
In most cases, the emphysematous process is localized in the left lung; it can cover the entire organ or mainly affect one lobe. The deformed lung practically does not function, sharply decreases in volume, loses elastic properties. The resulting displacement of the mediastinum leads to a significant disruption of pulmonary circulation and ventilation in a healthy lung, which provides the main gas exchange.
According to etiopathogenetic criteria, there are circulation, ventilation and circulation-ventilation forms of McLeod syndrome.
- The circulatory form is due to the presence of a unilateral vascular anomaly of the lungs. This may be a congenital absence (agenesis /aplasia) of one pulmonary artery with compensation of pulmonary circulation due to systemic circulation of the bronchi. Acquired pathology of the pulmonary artery is also possible due to its acute embolism and ischemia, postoperative thrombosis, as well as external compression of the vessel by intra-thoracic lymph nodes in tuberculosis.
- The ventilation form of McLeod syndrome is caused by the presence of congenital malformations of the respiratory parts of the bronchial tree (giant extensive emphysema with bronchomalacia, congenital bronchiectasis with dysgenesis of the respiratory tract) or acquired bronchopulmonary pathology (secondary obstructive emphysema as a result of incomplete blockage of a large bronchus by a tumor or foreign body; postinfectious or compensatory emphysema; progressive pulmonary dystrophy with destruction).
The development of the circulatory and ventilation form of McLeod syndrome is caused by hypoplasia of one of the pulmonary arteries. This condition is rarely observed, usually has a long latent course.
McLeod syndrome symptoms
McLeod syndrome can manifest at any age, usually manifests itself in adolescence and in adults. For congenital giant extensive emphysema, the early onset of McLeod syndrome is typical (during the newborn period and up to 4-5 years), with congenital bronchiectasis, the clinical onset usually occurs at the age of 8-12 years.
The disease occurs in a chronic form. There may be an asymptomatic or weakly expressed course. The manifestations of McLeod syndrome are nonspecific, similar to the symptoms of bronchitis and BEB. For no apparent reason, expiratory dyspnea appears, which gradually progresses. There is often a persistent cough with intermittent scanty sputum and diffuse chest pain, noticeable asymmetry of the chest. The release of copious sputum of a purulent nature indicates secondary infection. There may be periodic (ARVI-related) febrile episodes with increased bronchial phenomena and obstruction.
With congenital arteriovenous malformation and tuberculosis, McLeod syndrome can be accompanied by hemoptysis, paroxysmal cough attacks, hysterical shortness of breath with sharply rapid breathing, and the risk of asphyxia. McLeod syndrome is complicated by respiratory failure, bronchial obstruction of varying severity, the development of bronchial asthma and decompensated pulmonary heart disease.
Diagnosis of McLeod syndrome includes anamnesis collection, examination, radiography and CT of the lungs, bronchography, radioisotope scanning, external respiration examination. In the anamnesis of patients with McLeod syndrome, there are frequent cases of severe bronchopulmonary diseases. Visually, there is a deformation of the chest with a decrease in volume on the side of the lesion, percussion – displacement of the mediastinum in the opposite direction, a boxy tone of sound; auscultation – asymmetric breathing with weakening in the area of the affected lung, dry scattered wheezing, short-term crepitating noises, elongation of exhalation.
During lung x-ray, a pronounced unilateral increase in transparency (“super-transparency”) is noticeable lung tissue and a depleted lung pattern with areas devoid of it entirely (large bulls). Inspiratory and expiratory CT of the lungs helps to accurately identify thin-walled bullous formations in McLeod syndrome. The exhalation study shows an increase in the severity of changes in these areas – a symptom of an “air trap”. The shadow of the mediastinum at the height of inspiration deviates towards a healthy lung.
Bronchographically, signs of narrowing of the peripheral bronchi, indicating deforming bronchitis, are determined in the emphysematous lung. Angiopulmonography data indicate a unilateral decrease in the diameter of the trunk and branches of the pulmonary artery, an increase in the angles of their divergence, aplasia of the capillary network.
Lung scintigraphy reveals the absence of absorption of the radioisotope by the affected lung. The study of FER determines specific emphysematous changes, signs of bronchial obstruction, respiratory failure by expiratory type. Differential diagnosis of McLeod syndrome is carried out with simple hypoplasia or emphysema of the lung, bronchial asthma, COPD, complicated by spontaneous pneumothorax.
Treatment of McLeod syndrome
Treatment is determined by the degree of clinical manifestations and the rate of progression of pathology. Hospitalization and symptomatic therapy are indicated for the relief of respiratory failure and associated diseases. When respiratory purulent-inflammatory processes are layered, antibiotics are used. Additionally, oxygen therapy and physical therapy are carried out.
Surgical intervention is performed in case of a sharp violation of the emphysematous lung gas exchange function of a healthy lung or frequent infectious complications. The volume of resection is reduced to lobectomy or pneumonectomy. The prognosis of McLeod syndrome is determined by the frequency of bronchopulmonary infections and the level of development of respiratory failure, usually considered uncertain or unfavorable.
- Transfusion support for a patient with McLeod phenotype without chronic granulomatous disease and with antibodies to Kx and Km. Bansal I, Jeon HR, Hui SR, Calhoun BW, Manning DW, Kelly TJ, Lee S, Baron BW. Vox Sang. 2008 Apr;94(3):216-20. link
- A McLeod phenotype detected by random screening for K:-4 [Kp(b-)] blood donors in Brazil. Wendel S, Fontão-Wendel R, Levi JE, Aravechia MG, Bordokan RF, Russo D, Haddad MS. Transfusion. 2004 Nov;44(11):1579-87. link
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