Imaging Features to Distinguish Intralobar Versus Extralobar Bronchopulmonary Sequestration

To evaluate the CT characteristics of bronchopulmonary sequestration (BPS) and determine the imaging features in predicted hybrid lesions and sequestration subtypes (intralobar vs. extralobar sequestration).

This was a multicenter retrospective study in which all surgical pathology specimens of lung sequestration performed in a tertiary hospital system were reviewed from January 2008 to January 2026. In total, 52 pathologic samples of lung sequestrations were analyzed and compared with preoperative imaging features. Imaging features including anatomic and vascular anatomy, parenchymal changes and relationship to the pleural were noted. BPS with coexistingcongenital pulmonary airway malformation, also called a hybrid lesion, on pathology was correlated with imaging findings.

Venous drainage patterns differed significantly between the intralobar sequestration (ILS) and extralobar sequestration (ELS) groups, with 11% of the ILS group draining to the systemic venous system versus 57% of the ELS group (P=0.013). In addition, 98% of ILS were inseparable from the surrounding lung, whereas 57% were separate from the normal lung (P<0.001). Cystic changes were common; 7/12 cases of hybrid lesions had cystic abnormalities on CT, whereas 17 out of the 40 cases without pathologic evidence of hybrid lesions had cystic changes on CT.

Distinguishing intralobar from extralobar sequestration is imperfect based on venous drainage and separability from the normal lung parenchyma. Our data also showed a discrepancy between cystic abnormalities on CT and pathologically proven hybrid lesions, with a higher proportion of sequestrations with cystic changes on CT than were reported on pathologic analysis. Thus, hybrid lesions may be underdiagnosed on pathologic analysis.