BACKGROUND Sequestration with associated cystic adenomatoid malformation is rare. A study was undertaken to determine whether pulmonary sequestration associated with congenital cystic adenomatoid malformation has a more favourable natural history than that of sequestration without associated cystic adenomatoid malformation.

RESULTS In five infants in whom an antenatal ultrasound scan had detected a congenital lung malformation at 18–19 weeks gestation a final diagnosis of extralobar or intralobar pulmonary sequestration with congenital cystic adenomatoid malformation was made postnatally. Postnatal ultrasound and computerised axial tomographic scans confirmed the diagnosis of sequestration by delineating anomalous vascular supply. Cystic changes were also observed in the basal area of the sequestration in all patients. Four children remained asymptomatic and one infant presented at 10 months of age with pneumonia. The mean age at surgical resection was 6.8 months (range 2–10). Histopathological examination confirmed intralobar pulmonary sequestration with associated Stocker type 2 congenital cystic adenomatoid malformation in two patients and extralobar pulmonary sequestration with associated Stocker type 2 congenital cystic adenomatoid malformation in three patients. The mean period of follow up was four years (range 1–8). The children remain well and are developing normally.

CONCLUSIONS The importance of seeking an anomalous blood supply in children with congenital lung lesions is emphasised. Pulmonary sequestration and congenital cystic adenomatoid malformation probably share a common embryogenesis despite diverse morphology. The natural history of antenatally diagnosed lung masses is variable. Early postnatal surgical resection of pulmonary sequestration with cystic adenomatoid malformation is recommended. Surgical excision should be conservative, sparing the normal lung parenchyma.