Bilateral Intralobar Sequestration of the Lung with a Bridging Isthmus: Pathologic and Radiologic Findings

A 4-year-old boy presented with pneumonia. Computed tomography demonstrated a multicystic mass at the posteromedial bilateral lower lobe segments, which were connected by a bronchus behind the heart. Enhanced computed tomography revealed that an anomalous artery arose from the left gastric artery and inserted into the left sequestrated lung and branched to the right one. The diagnosis of bilateral intralobar sequestration (ILS) with a bridging isthmus was made. After removal of the bilateral ILS, radiologic and pathologic approaches were undertaken to reconstruct the vascular and bronchial architectures. The following observations were made: (1) histologically, the region near the anomalous artery insertion site contained bronchial structures, which looked like an ectopic pulmonary hilus. This bronchial structure was continuously observed in the isthmus and its opening of the right sequestrated lung; (2) radiologically, the shape and course of the bronchi within the ILS indicated a distinct bronchial origin that arose from the pulmonary hilus-like structure, and the anomalous artery that ran along with those bronchi, resembled a pulmonary artery. These features suggested that this bilateral ILS might have originated from an accessory lung tissue.