Bronchogenic Cysts.

 

Bronchogenic Cysts

PKGhatak, MD

Bronchogenic cysts are rare in adults but not so uncommon in newborns and young children. In a 3 to 6 week old fetus, two independent lateral lung buds develop as outpouchings from the ventral wall of the primitive foregut. (1).  Each of these two lateral buds differentiates as right and left main bronchi. The primitive foregut differentiates into the trachea and esophagus by developing a deep groove and joining the laryngotracheal sulci of the lateral wall of the foregut. Each main bronchi rapidly grows in the surrounding mesenchymal tissue and branches repeatedly and forms the rest of the conductive airways. Bronchogenic cysts arise from the development errors of the bronchogenic cells. Some of the bronchogenic cells remain attached to the developing foregut and that is the reason the bronchogenic cysts appear outside the thorax as these cells form cysts.

The bronchogenic cyst develops as a small solid mass and then as proteinous mucus begins to accumulate and it takes a cystic appearance. The walls of the cysts are thin and cysts have no ducts. As the cyst enlarges it compresses the adjoining structures - trachea, bronchi, and blood vessels in the middle mediastinum. Symptoms vary from being totally asymptomatic to cardiopulmonary compromise.

 Incidence: one in 50,000 hospital admission. Location: 10 % of bronchogenic cysts are located in the middle mediastinum. The mediastinal cysts account for 50 % of all lung cysts and are seen in the paratracheal, carinal, para-esophageal and hilar region. 20 % of bronchogenic cysts are intrapulmonary and develop late and are seen in adults. Other locations are the neck, pericardial, pleural, diaphragm, and retroperitoneal. Size of the cysts: 2 to 10 cm in diameter, usually single.

Cysts are lined with ciliated pseudostratified columnar respiratory epithelium and squamous metaplasia is rarely present. In addition to mucus glands, cartilage, smooth muscle and blood may be present.

 Symptoms in children: Stridor, shortness of breath, dysphagia, superior vena cava syndrome, pneumothorax and pneumonia. In adults: Most cysts are asymptomatic detected in chest x-rays, and recurrent pneumonia.

 Complications: Fistula formation in the tracheobronchial tree, malignancy. Diagnosis: The present generation of sonograms is very sensitive and can detect bronchogenic cysts in utero. In newborns to adults, the chest x-ray and CT scan detect all bronchogenic cysts, rarely MRI is needed.

Treatment: Surgery is the only option in symptomatic cases and in adults lobectomy is usually required for intrapulmonary cysts. Surgery is also recommended for asymptomatic cysts before the start of complications.

Reference: 1.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5320013/

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