CT and histopathological correlation of congenital cystic pulmonary lesions: a common pathogenesis?

To determine whether similarities exist in both the imaging and histopathological features of congenital cystic lung lesions and whether a more appropriate classification would be to adopt the theory of "malinosculation".

From the histopathology and computed tomography (CT) database, 24 patients (16 male, median age 3 years) with congenital cystic lung lesions were identified. CT studies were reviewed for site and characteristics of the lesions, parenchymal features, bronchial anatomy, and the presence of a feeding systemic vessel. Individual histopathological parameters were also correlated with CT data.

There were five type 1 congenital cystic adenomatoid malformations (CCAMs), six type 2 CCAMs, one type 4 CCAM, one bronchial atresia, four pleuropulmonary blastomas (PPBs), and seven sequestrations. CCAMs (types 1, 2 and 4), sequestrations and PPBs appeared as cystic lesions, with cyst size less than 2 cm in type 2 CCAMs. Sequestrations were distinguished radiologically from CCAMs by systemic vessels. Reduced pulmonary attenuation was seen in bronchial atresia, type 2 CCAMs and in sequestrations. Histopathology showed an overlap in entities with sequestrations demonstrating CCAM type 2 histology and segmental atresia noted in both type 2 CCAMs and sequestrations. PPBs showed histological and imaging overlap with type 4 CCAMs and were distinguished on histology by the presence of blastematous proliferation.

This study demonstrates overlap in the CT appearances of congenital cystic lesions. The similarity in CT and histopathology findings across the spectrum of developmental lesions supports the hypothesis of a common aetiology.