Congenital Lung Cysts
Congenital lung cysts may be differentiated into three groups bronchogenic cysts that result from abnormal budding and branching of the tracheobronchial tree during its development, alveolar, and combined forms. Bronchogenic cysts are characterized by respiratory cell mucosa composed of either columnar or cuboidal ciliated cells that line the cavity. They may lie outside the normal lung structure or within it. These cysts do not communicate with the tracheobronchial tree unless they become infected. Bronchogenic cysts must be distinguished from acquired bronchiectasis, which is more common in the dependent portions of the lung; in multiple congenital cysts, the upper lobes are often the site of the disease. The differential diagnosis also includes neurenteric cysts, which are associated with vertebral body anomalies, gastroenteric duplication cysts, congenital lobar emphysema, acquired cysts complicating pulmonary interstitial emphysema, and bronchopulmonary dysplasia.
The cysts are typically located near the carina but may occur in the paratracheal, carinal, hilar, or paraesophageal areas. The location of the cyst is important in determining the clinical presentation. Intrapulmonary cysts with a communication between a cyst and the tracheobronchial tree may incorporate a check valve mechanism, which may result in rapid expansion of the cyst. If they are centrally located, they may produce symptoms (coughing and wheezing, particularly during crying) in the neonatal period because of compression of the trachea or main bronchi. Cysts located in the periphery usually present with infection or hemorrhage later in life or are discovered by chance on a chest radiograph.
Congenital Cystic Adenomatoid Malformation of The Lung
This lesion consists of a mass of cysts lined by proliferating bronchial and cuboidal epithelium. It is divided into three types: type I, which includes multiple large, thin-walled cysts; type II, which includes multiple, evenly spaced cysts; and type III, which includes a bulky ﬁrm mass with small, evenly spaced cysts. The lesion is now frequently diagnosed by antenatal ultrasonography, but some so detected may regress during the third trimester. Approximately 25% of patients are stillborn; they are usually hydropic and have a type III lesion. Fifty percent are born prematurely. Infants may develop respiratory distress immediately after birth, depending on the size of the lesion; other presentations include recurrent infection, hemoptysis, and an incidental ﬁnding on the chest radiograph. The lesion may also be premalignant. Infants with life-threatening respiratory distress require surgery in the perinatal period.
The treatment of patients with asymptomatic disease is controversial, but intervention in infancy should be considered because of the increased risk of infection, pneumothorax, and malignancy.
Congenital Pulmonary Lymphangiectasis
In this condition, there is dilatation of the lymphatic vessels of the lungs and obstruction to their drainage.
It may be associated with lymphedema in other portions of the body. Most infants with this problem develop severe respiratory distress at birth, and the majority of them die. Radiologic ﬁndings include a ground-glass appearance with ﬁne, diffuse, granular densities representing dilated lymphatics; as with other congenital pulmonary abnormalities, there may be delayed resolution of lung ﬂuid. On examination, the lungs are bulky, with pronounced lobulation, and they contain many thin-walled cystic space dilated lymphatic vessels.