Congenital Lung Abnormality

Congenital lung abnormalities are being detected more frequently at routine high-resolution prenatal ultrasonography. The most commonly encountered anomalies include lung agenesis-hypoplasia compllex (pulmonary underdevelopment), congenital pulmonary airway malformation, congenital lobar overinflation, bronchial atresia, bronchogenic cyst, congenital high airway obstruction syndrome, scimitar syndrome and bronchopulmonary sequestration. Recognizing the antenatal and postnatal imaging features of these abnormalities is necessary for optimal prenatal counceling and appropriate perinatal and postnatal management.

With advances in both fetal ultrasonography and magneting resonance imaging, abnormalities of the thorax are increasingly being recognized antenatally, allowing providers to anticipate managementy issues at the time of delivery or later in neonatal life, and help parents comprehend the prognosis. Recognizing the imaging features of a variety of intra thoracic processes in the fetus is necessary for appropriate guidance of the clinicians caring for the mother.

Congenital thoracic anomalies range from abnormal lung with normal vasculature (e.g, congenital lobar over inflation) to abnormal vasculature with normal lung (e.g, hypogenetic lung syndrome, bronchopulmonary sequestration).  The vascular abnormality (e.g,  absent pulmonary artery associated with pulmonary agenesis) may be the underlying cause of the malformation).

The most commonly encountered anomalies can be classified into three broad categories: bronchopulmonary (lung bud) anomalies, vascular anomalies and combine lung and vascular anomalies. Bronchopulmonary anomalies include lung agenesis-hypoplasia complex (pulmonary underdevelopment), congenital pulmonary airway malformations, congenital lobar overinflation, bronchial atresia and bronchogenic cysts. Vascular anomalies include absence of the main pulmonary artery, anomalous origin of the left pulmonary artery or pulmonary sling, anomalous pulmonary venous drainage and pulmonary arteriovenous malformations. Combined lung and and vascular anomalies include scimitar syndrome and bronchopulmonary sequestration. Vascular abnormalities may accompany bronchopulmonary abnormalities in some cases: for example, pulmonary vascular abnormalities with pulmonary hypoplasia or agenesis, or a systemic arterial supply to a small cysts congenital pulmonary airway malformations.

Understanding the pathogenesis  of broncho-pulmonary malformations is difficult and confusing. according to one long-held theory, many of these lesions are due to defective foregut budding and differentiation. Another theory of causation is that these lesions are related to airway obstruction with secondary pulmonary dysplastic