Bronchogenic cyst

Bronchogenic cysts (BCs) are congenital malformations resulting from abnormal budding of the foregut and are most commonly found in the mediastinum. They are usually located within the mediastinum at an early stage of gestation or in the lung at a later stage. However, their location can be anywhere along the developmental pathway of the foregut in an ectopic site.

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Epidemiology

Bronchogenic cysts are rare cystic lesions, with prevalences of 1 per 42,000 and 1 per 68,000 admissions in two hospital series. They are slightly more frequent in men and often remain undiscovered until the third or fourth decade of life. They account for 10% to 15% of mediastinal tumors and 50 to 60% of all mediastinal cysts.

Types

Classification of mediastinal bronchogenic cysts is in five types according to their location:

• Paratracheal
• Carinal
• Paraesophageal
• Hilar
• Miscellaneous

Intrapulmonary bronchogenic cysts represent 20% to 30% and most commonly involve the lower lobes. They have no predilection for the right or left side. The other locations of bronchogenic cysts are rare and include the pericardium, the pleura, the neck, the diaphragm, and the retroperitoneum.

cause

The genesis of bronchogenic cysts is from the abnormal or late budding of the embryonic ventral lung bud or the tracheobronchial tree which occurs between the 26th and 40th days of gestation. This abnormal bud subsequently differentiates into a fluid-filled, blind-ending pouch. The location of a bronchogenic cyst depends on the embryological stage of development at which the anomaly occurs. When the abnormal budding happens during early development, the cyst occupies the tracheobronchial tree. Cysts that arise later are more peripheral and may involve the lung parenchyma.

Signs and symptoms

In pediatric patients: bronchogenic cysts may cause life-threatening compressive symptoms.

• Symptoms are secondary to cyst infection or compression of adjacent structures.
• Fistulized bronchogenic cysts cause cough, fever, sputum production, and hemoptysis.
• Non-fistulized bronchogenic cysts are usually responsible for chest pain.
• Pericystic pneumonitis or pneumonia in the adjacent compressed lung are responsible for fever and shortness of breath.

Diagnosis

Chest radiograph: Pulmonary bronchogenic cysts: Sharply defined, solitary, round or oval opacities, usually the lower lobe. They can present as a homogeneous water density, as an air-filled cyst, or with an air-fluid level. Abnormalities in the surrounding lung parenchyma, atelectasis or consolidation may occur and may make the diagnosis more difficult.

Mediastinal bronchogenic cysts: Homogeneous, smooth, solitary, round or ovoid masses usually in the middle mediastinum.

Computed tomography scan: CT is the investigation of choice. The CT density of bronchogenic cysts is variable from typical water density to high density related to blood, increased calcium content, anthracotic pigment, or increased protein content of the fluid.

Magnetic resonance imaging (MRI): Magnetic resonance imaging is better than CT scan at delineating anatomic relations and the definition of the cyst.

Treatment

The treatment of patients with bronchogenic cysts depends on symptoms at presentation and the patient’s age. Surgical resection alleviates symptoms, prevents complications and establishes the diagnosis of bronchogenic cysts. Symptomatic cysts should be resected either by thoracotomy or via video-assisted thoracoscopy regardless of patient age unless surgical risks are unacceptably high.

Intrapulmonary bronchogenic cysts: Lobectomy is the procedure of choice. However, in peripheral bronchogenic cysts or patients with limited lung function, a conservative procedure as a total pericystectomy, a wedge resection, or segmentectomy are recommended.

Mediastinal bronchogenic cysts: The presence of adhesions especially in complicated forms of mediastinal bronchogenic cysts can lead to incomplete resection. Thus, resection or destruction of the mucosa is a requirement to prevent accumulation of fluid and late recurrence. An alternative option for bronchogenic cysts is close imaging surveillance to ensure temporal stability.

Prognosis

The prognosis of bronchogenic cysts after surgical excision is excellent. In case of incomplete excision, late recurrences can occur.A recent study reviewing 102 patients treated for bronchogenic cysts, the estimated mean morbidity and mortality was 20%.

NIH genetic and rare disease info

• NIH info on Bronchogenic cyst

Bronchogenic cyst is a rare disease.

Bronchogenic cyst Resources
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