Bronchogenic Cysts
Marianna M. Sockrider, MD, DrPH, FAAP
Introduction/Etiology/Epidemiology
•Bronchogenic cysts are congenital malformations of the lung. They are
a type of foregut duplication cyst derived from abnormal budding of the tracheal diverticulum before 16 weeks of gestation.
•A bronchogenic cyst is a closed sac typically made up of respiratory- type epithelium. It may have any of the elements normally present in the trachea and bronchi, including fibrous connective tissue, mucous glands, smooth muscle, and cartilage in the wall. There can be squamous metaplasia.
•Usually there is a single unilocular cyst filled with clear fluid or mucus. However, there can be multilocular and multiple cysts at times.
•It is the most common type of lung cyst in infancy, although it may not appear until adulthood.
•The exact incidence is not known, but it has been estimated that bronchogenic cysts make up 14%–22% of congenital lung cysts and 10% of mediastinal masses in children.
•Mediastinal cysts occur equally in male and female patients; intrapulmonary cysts may be more common in male patients.
Pathophysiology
•The most common location is in the mediastinum. About half are located within about 3 cm of the carina, most often on the right side (Figure 20-1).
•There are 5 groups based on location:
—Paratracheal cysts
—Carinal cysts
—Paraesophageal cysts, which may communicate with the esophagus
—Hilar cysts, which come off the main or lobar bronchi or can migrate into the lung parenchyma
—Miscellaneous cysts, which are rare, having migrated during embryonic development to unusual sites such as abdominal, cervical, retroperitoneal, and subcutaneous locations
•Mediastinal cysts may communicate with the tracheobronchial tree.
•A few patients have had a systemic blood supply.
•Bronchogenic cysts can progressively enlarge in utero with advancing gestation and over time after birth.
•Bronchogenic cysts can cause symptoms due to mass effect, direct pressure on an airway that leads to air trapping, or secondary infection.
—Compression of the bronchus or esophagus may occur even with a small cyst (1.5–3.0 cm).
—Compression with a large cyst in utero may result in pulmonary hypoplasia of the adjacent lung.
Clinical Features
Clinical manifestations vary with location and size.
•Up to 20% of bronchogenic cysts remain asymptomatic and may only be detected as an isolated, incidental finding on a chest radiograph— typically appearing as a mediastinal mass.
•Most symptomatic cysts appear in infancy or early childhood; however, symptoms can develop at any age.
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