Bronchogenic cyst is a malformation of small bronchi, which is a thin–walled cavity formation filled with mucous secretions of bronchial glands. Bronchogenic cyst may be asymptomatic or manifest signs of compression of the trachea, bronchi, esophagus (cough, shortness of breath, cyanosis, chest pain, dysphagia, etc.). In diagnostic terms, the most informative are polypositional radiography, linear and computed tomography, bronchography, bronchoscopy, ultrasound of the mediastinum. Treatment of bronchogenic cysts is operative – cystectomy, segmental resection of the lung, lobectomy.
Q32.4 Other congenital anomalies of the bronchi
Bronchogenic cyst is a congenital cystic formation that has a genetic connection with the bronchial tree and repeats its morphological structure. Among all lung and mediastinal tumors, the proportion of bronchogenic cysts is 2-13%. Statistically, they are more often detected in young and middle-aged men, but they can clinically manifest themselves even in children (including newborns) and adolescents. In some cases, bronchogenic cysts develop completely asymptomatic, in others they acquire a rapidly progressive and complicated course that requires an emergency surgical response. The potential risk of complications causes the need for early diagnosis of bronchogenic cysts and their timely planned treatment.
Bronchogenic cyst causes
Like other lung malformations, a bronchogenic cyst is formed due to a violation of embryogenesis. It is believed that this pathology is based on a defect in the separation of the primary intestine into digestive and respiratory tubes. Exactly what factors contribute to the occurrence of this violation is not known for certain. The cells of the primary intestine can be implanted into the rudiments of any organs, which causes the localization of bronchogenic cysts not only in the trachea and bronchi, but also in the heart, esophagus, pancreas, diaphragm, etc.
For the most part, bronchogenic cysts have a rounded or ovoid shape, a single-chamber structure; the average size of the formations is 6-10 cm. The cyst wall is thin (3-5 mm), its inner surface is represented by a shimmering cylindrical epithelium of the bronchi (less often a flat or cubic epithelium). Often, the cyst wall completely repeats the structure of the tracheal or bronchial wall and contains loose connective tissue, mucous glands, smooth muscles, hyaline cartilage, vessels, nerve fibers and adipose tissue. In uncomplicated cases, bronchogenic cysts are filled with muco-gelatinous, transparent or slightly cloudy fluid. When infected, the contents of the cyst become purulent.
In pulmonology, bronchogenic cysts are usually classified depending on the size, localization, connection with the tracheobronchial tree and the nature of the course. The sizes of cysts vary from small (less than 5 cm in diameter) to giant (up to 20 cm or more), squeezing the pulmonary parenchyma and causing atelectasis of the lobe or the whole lung. According to the location , bronchogenic cysts are divided into:
- tracheobronchial (paratracheal, bifurcation and basal)
- esophageal (paraesophageal and intramural)
- detached bronchogenic cysts with atypical localization (okolodiaphragmal, intrapleural, parapancreatic, etc.)
Mediastinal cysts are more often detected in the posterior and anterior mediastinum, less often in its other departments. Depending on the presence of communication with the trachea and bronchi, closed (non-draining) and open (draining) bronchogenic cysts are isolated. The last of them, in addition to the mucous contents, also contain air. The course of cysts can be smooth, uncomplicated or complicated (compression syndrome, infection, breakthrough into the pleural cavity or bronchus).
Bronchogenic cyst symptoms
Approximately 30% of the formations develop asymptomatically and are detected during preventive fluorography. The remaining patients have various clinical manifestations due to localization, cyst size and the presence of complications.
Thus, closed tracheobronchial cysts can cause a dry, intrusive cough, and those communicating with the bronchus can cause a cough with mucous sputum. The most vivid clinical picture is given by bronchogenic cysts located in the tracheal bifurcation area. In this case, in addition to the phenomena of tracheobronchitis, signs of compression of the tracheobronchial tree develop early: inspiratory shortness of breath, cyanosis, chest pain. Bronchogenic cysts of esophageal localization cause dysphagia when they reach certain sizes. Pericardial cysts often provoke persistent sinus tachycardia and extrasystole, ECG changes in the form of focal blockade of the legs of the Gis bundle.
When the cyst is infected, a high fever appears, pronounced signs of purulent intoxication. When the purulent contents break through into the bronchi, a cough with purulent sputum occurs, aspiration pneumonia may develop, and in children there is a threat of asphyxia. Among the complications of bronchogenic cysts, suppuration, pulmonary bleeding, pneumothorax and hydropneumothorax, compression of mediastinal organs (including superior vena cava syndrome), lung atelectasis are most common. A rare, but quite likely complication may be the malignancy of a bronchogenic cyst.
Due to the fact that clinical symptoms may be absent, and physical data are nonspecific, instrumental studies are crucial in the diagnosis of bronchogenic cysts. With the help of ultrasound of the mediastinum, the localization, shape, contours, dimensions, topographic and anatomical relationships of the volumetric formation are clarified and its origin is assumed.
With polypositional chest x-ray, in typical cases, a spherical or oval homogeneous shadow of medium intensity, with clear contours, is determined. When applying the shadow of the mediastinum to the shadow of the cyst, pneumomediastinography or radiography of the esophagus with barium suspension is additionally required. Bronchoscopy and bronchography allow to establish anatomical relationships of a bronchogenic cyst with a tracheobronchial tree. If there are signs of compression of the superior vena cava or thoracic lymphatic duct, it is advisable to perform phlebography and lymphography.
A distinctive feature of thin-walled bronchogenic cysts is a change in their configuration and position when gas is injected into the mediastinum or pleural cavity (unlike dermoid cysts with a thick wall or dense tumors of the mediastinum). MSCT of the chest in some cases allows you to abandon the invasive diagnosis of bronchogenic cysts and plan the scope of intervention in advance, since it provides comprehensive information about the localization and size of the formation.
A full range of diagnostic measures provides accurate differential diagnosis even at the preoperative stage, allowing you to reject terato-dermoid formations, thymomas, neurinomas, coelomic cysts of the pericardium and other mediastinal tumors.
Bronchogenic cyst treatment
The tactics of observation and conservative treatment of bronchogenic cysts are ineffective and risky. Given the high probability of serious complications (perforation, bleeding, suppuration, compression of mediastinal organs, etc.), the optimal method is elective surgery.
Conditionally conservative tactics can be used at the stage of preparing patients for surgical treatment. It may include detoxification and antibacterial therapy, bronchoscopic catheterization or percutaneous puncture of the cyst with aspiration of pus and sanitation of the cavity during suppuration, drainage of the pleural cavity (when the cyst breaks), etc.
The scope of the surgical aid varies from cystectomy to segmental resection of the lung or lobectomy. With a draining bronchogenic cyst, a defect in the bronchial wall is sutured. Most often, thoracic surgeons perform a thoracotomy from an anterolateral or lateral access. In recent years, bronchogenic cysts have been increasingly removed using thoracoscopic surgery.
Prognosis and prevention
The outcomes of operations in most cases are favorable. Postoperative complications include bronchial fistulas, intrapleural bleeding, pneumonia, pleural empyema. As a rule, they occur in patients operated on for suppuration of a bronchogenic cyst. Among children, the mortality rate is about 5%.Due to the poorly studied etiology of congenital formations, it is recommended to avoid teratogenic effects during the gestation period.
- Clinical features and treatment of bronchogenic cyst in adults. Liu HS, Li SQ, Cao ZL, Zhang ZY, Ren H. Chin Med Sci J. 2009 Mar;24(1):60-3. link
- Pulmonary and mediastinal bronchogenic cysts: a clinicopathologic study of 33 cases. Limaïem F, Ayadi-Kaddour A, Djilani H, Kilani T, El Mezni F. Lung. 2008 Jan-Feb;186(1):55-61. link
- Diagnosis and surgical treatment of bronchogenic cysts. Ge F, Liao Q, Xiao S, Ren H, Zhang Z, Li Z. Chin Med Sci J. 1995 Mar;10(1):61-2. link
- Bronchogenic cysts of the lung. Ribet ME, Copin MC, Gosselin BH. Ann Thorac Surg. 1996 Jun;61(6):1636-40. link
- Esophageal bronchogenic cyst and review of the literature. Altieri MS, Zheng R, Pryor AD, Heimann A, Ahn S, Telem DA. Surg Endosc. 2015 Oct;29(10):3010-5 link