A routine 20-week antenatal ultrasound scan showed a congenital lesion of the left fetal lung, measuring approximately 25 mm x 25 mm x 30 mm. The mass showed no sonographic change through the remainder of an uneventful pregnancy. The baby was delivered by elective caesarean section at 38 weeks' gestation, with a birth weight of 2 900 g, and had no postnatal complications. A chest radiograph performed in the early neonatal period was normal, but a contrasted single-slice helical computed tomography (CT) chest scan at age 6 weeks demonstrated the small, oval, solid mass in the left lower lobe, with no associated mediastinal shift (Fig. 1). The vascular supply of the lesion could not be identified on this scan
