Tracheal bronchus is a congenital anomaly of the structure of the tracheobronchial tree, in which the additional, lobar or segmental bronchus departs from the trachea above the place of its bifurcation or the main bronchus. It proceeds asymptomatically or according to the type of chronic, often recurrent inflammatory process in the lung, manifested by episodes of coughing with purulent sputum, chest pain, fever, hemoptysis. It is diagnosed by bronchoscopy, bronchography, CT, MRI, chest x-ray. In case of violations of the ventilation and drainage functions of the abnormal bronchus, surgical correction of the defect is performed.
Tracheal bronchus refers to rare malformations of the respiratory system. The detection rate is 0.1-5% of all bronchoscopy, bronchography and CT examinations of the thoracic cavity. Men suffer more often than women. The anomaly is formed mainly in the right part of the trachea, the left-sided location is very rarely detected. The mouth of the pathological bronchus is located 2-6 cm above the bifurcation. The length of the organ is from 6 to 20 mm, the diameter is from 5 to 10 mm. Pathology can be combined with arteriovenous malformations of the lung, other malformations of the bronchopulmonary, gastrointestinal, musculoskeletal and cardiovascular systems. It is often found in patients with Down syndrome.
Causes of tracheal bronchus
The etiology of the malformation is not fully established. Anomalies of the branching of the tracheobronchial tree are the result of a violation of embryogenesis, formed at 6-8 weeks of pregnancy under certain adverse circumstances. There are the following teratogenic factors that provoke the occurrence of congenital defects of the respiratory tract:
- External (exogenous). Anomalies of organs and systems are formed under the influence of physical, chemical and biological causes. The most dangerous physical effect on the developing embryo is ionizing radiation. The most common chemical factors of dysembriogenesis are alcohol consumption, tobacco smoking, and the use of a number of medications. Biological teratogens include toxins of some bacteria, viruses and protozoa.
- Internal (endogenous). Genetic breakdowns, hormonal status disorders, endocrine pathology and gestosis in pregnant women often lead to a violation of embryogenesis. Often, the prerequisite for the formation of congenital malformations is the age of one or both parents over 35 years.
The mechanism of the anomaly is not fully understood. It is known that aberrant tracheal processes form in embryos during 1-2 months of pregnancy. Then they presumably regress. The tracheal process, which has not undergone reverse development, is transformed into an abnormal bronchus. Subsequently, due to architectural defects, its ventilation and drainage functions are disrupted. A chronic inflammatory process develops in the corresponding part of the lung tissue, bronchiectasis is formed. The tracheal bronchus in its structure corresponds to ordinary bronchi of the appropriate caliber. Unlike other anomalous formations of large airways, its wall contains cartilaginous rings.
Many authors of scientific articles from the field of pulmonology in their classification distinguish the transposition or separation of the upper lobe bronchi, as well as the presence of an overcomplicated organ. A pathological branch of the trachea may end blindly, aerate an additional lobe, a section of the upper lobe, an additional lung, or communicate with a cystically altered pulmonary parenchyma. In accordance with the simplest and most popular classification of clinical significance, tracheal bronchus is:
- Displaced (dislocated). The structure of the lungs is not disturbed, the upper lobe is ventilated by no more than three segmental bronchi.
- Additional (super-complete). There is an additional bronchus communicating with an additional lobe, lung or cystic cavity.
Tracheal bronchus symptoms
In most cases, there are no clinical signs of this congenital anomaly. Tracheal additional or displaced bronchus is detected accidentally during examination or surgical intervention for another reason. In some patients, a violation of aeration leads to the appearance of an inflammatory or suppurative process in the lung area ventilated by the pathological bronchus. The first symptoms of the disease usually appear in adulthood. The patient is concerned about recurring episodes of cough with yellow-green sputum, subfebrile or febrile fever, pain in the corresponding half of the chest.
Sometimes the process takes a prolonged course, cough with sputum, shortness of breath during exercise, pain syndrome are observed for a long time. There are symptoms of general intoxication. The patient complains of an increase in body temperature to subfebrile values, a decrease in appetite and gradual weight loss, increased fatigue, weakness. With a prolonged chronic course of the inflammatory process, the terminal phalanges of the fingers thicken according to the type of drumsticks, the nails take the form of watch glasses. In a number of patients, hemoptysis occurs and recurs.
The tracheal bronchus, unable to fully ventilate, can provoke the occurrence of pneumonia, contribute to the development of a tuberculous or oncological process in the corresponding part of the lung. The combination of this anomaly of the structure of the respiratory tract with vascular malformations leads to hemoptysis, recurrent, sometimes massive pulmonary bleeding. During a frontal or pulmonectomy, such a bronchus is often mistaken for a vessel and is not subjected to the necessary treatment. Because of this, an undiagnosed pathology becomes the cause of a postoperative complication – a tracheal fistula is formed.
Patients with suspected tracheal bronchus are examined by a pulmonologist, if necessary, they are consulted by a thoracic surgeon, a phthisiologist, an oncologist. The examination helps to identify signs of chronically ongoing inflammatory lesions of the respiratory organs – lip cyanosis, distal hypertrophic osteoarthropathy. With percussion, the shortening of the pulmonary sound is determined in the projection of the affected area, dry and wet wheezes are also heard there. The final diagnosis is made on the basis of:
- Bronchological examination. Fibrobronchoscopy and bronchography are performed. Bronchoscopy allows you to detect an incorrectly located (above the carina) mouth of the bronchus. With the help of bronchography, the variant of the abnormal organ (overcomplete or dystopian) is clarified, its diameter and length are determined, patency is assessed, the architectonics of the tracheobronchial tree is studied.
- Radiation methods. It is possible to suspect tracheal bronchus on an lung x-ray in the presence of a long-existing local infiltration or recurrent pneumonia in the same lung area. CT and MRI of the lungs reveal an abnormal variant of tracheal branching, detect pathological changes in the lung tissue communicating with the bronchus and bronchiectasia.
- Angiopulmonography is used to diagnose vascular malformations often associated with this pathology. If tuberculosis of an insufficiently ventilated area of the lung is suspected, sputum examination is performed – a simple bacterioscopy, culture on nutrient media, determination of mycobacterium DNA using express diagnostic methods.
Tracheal bronchus treatment
The asymptomatic existence of an anomaly indicates the normal ventilation function of the bronchus, treatment in this situation is not prescribed. If the tracheal overcomplete bronchus is the cause of chronic inflammation, suppurative process of the additional lobe or lung, surgical removal of the affected area is performed together with the bronchus aerating it. Other indications for resection of a lobe, segment or lung are recurrent hemoptysis and (or) pulmonary bleeding, bronchiectasis, neoplastic process. In recent years, surgical interventions are increasingly performed using minimally invasive videothoracoscopy.
Prognosis and prevention
The prognosis depends on the condition of the ventilated pulmonary parenchyma. Timely surgical resection of a site of cystic hypoplasia, bronchiectasis or a zone of chronic inflammation leads to complete recovery. The malignant neoplasm may recur in another part of the lung or in the opposite organ. Concomitant vascular abnormalities are often present simultaneously in several segments, lobes, or both lungs, therefore, despite surgical intervention, pulmonary bleeding can sometimes recur.
Primary prevention of abnormal branching of the trachea has not been developed. A healthy lifestyle of a pregnant woman significantly reduces the risk of the formation of any malformations in the fetus. The expectant mother is recommended to give up alcohol, tobacco and other toxic substances, avoid contact with infectious patients, take medications strictly as prescribed by a doctor. A patient with a diagnosed pathology needs regular medical examinations, an annual X-ray examination of the chest organs.
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