Revising the classification of lung sequestrations

The classification of lung sequestrations distinguishes between extralobar and intralobar types, according to their venous drainage - systemic vs pulmonary - and the presence or absence of independent pleura. However, imaging, surgical and/or pathological findings often differ from this description. The objectives of this article are to quantify the percentage of lung sequestrations that do not fit the classic description of extra- and intralobar types and to evaluate the accuracy of the currently used classification.

A retrospective search identified all children with a confirmed lung sequestration diagnosed and treated in our Hospital over the last 10 years. Two senior pediatric radiologists reviewed their contrast-enhanced computed tomography chest scans and evaluated the main anatomical features that define sequestrations, including pleura, arterial and venous pattern, airways and lung parenchyma. We compared the imaging-, surgical- and pathological findings to those described for extra- and intralobar sequestrations.

25 children (20 M, 5 F) conform the series. Only 13 lesions (52%) filled all criteria described for an extra- or intralobar sequestration. The remaining 12 lesions (48%) had at least one differing criteria, including incomplete independent pleura (n = 2; 8%), mixed systemic and pulmonary arterial supply (n = 1; 4%) or venous drainage (n = 3; 12%), normal connection to airway (n = 1; 4%) and/or coexistent congenital lung anomalies (n = 11; 44%).

Lung sequestrations seem to represent a spectrum of anomalies rather than separated entities. Therefore, a detailed description of their main anatomical features could be more relevant for clinicians and surgeons that the rigid distinction in intra- and extralobar sequestration currently applied.