Congenital cystic adenomatoid malformation in an extremely low birthweight infant

A baby girl was born prematurely at 24 weeks and 3 days of Gestation because of her mother's premature membrane rupture and intrauterine infection. She underwent artificial respiratory support for respiratory distress syndrome in the neonatal intensive care unit. A chest radiograph showed a low attenuation area in the left lower lung field 4 days after birth, and the area gradually enlarged. Chest CT revealed a pulmonary cystic lesion in the left lingual division that pressed on the residual intact lung and mediastinum. Percutaneous arterial oxygen saturation fell to 90% or less when she cried. Left upper lobectomy was performed under a suspicion of congenital cystic adenomatoid malformation at 185 days after birth. Histopathological examination revealed the cystic lesion to be focally lined with respiratory epithelium and smooth muscle layers. The features were suggestive of type I congenital cystic adenomatoid malformation.