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.
