Abstract
Congenital cystic adenomatoid malformation is a rare pulmonary lesion that can be diagnosed prenatally by ultrasonography. This hamartomatous pulmonary mass is typically unilateral and usually involves one lobe or segment of the lung. Hamartomas are rare tumors of variable physical appearance, whose sonographic appearance is usually that of a predominantly cystic or solid mass. Typically slow growing, it is not uncommon for focal calcifications to develop. On rare occasion, hamartomas may be bilateral or involve the entire lung. Pulmonary sequestrations probably represent bronchopulmonary foregut abnormalities. Extralobar lesions are the least common overall, but are the most common form found in neonates and nearly the only form that has been detected prenatally. Sequestrations occur most commonly on the left (90%) in the posterior and basal segments. Subdiaphragmatic lesions (which account for 2.5% of bronchopulmonary foregut malformations) have been observed prenatally associated with other anomalies, including foregut abnormalities and congenital diaphragmatic hernia in 58% of cases. This form of sequestration has rarely been diagnosed prenatally. The following case report illustrates cystic adenomatoid malformation in extralobar pulmonary sequestration.