Computed tomography findings of extralobar pulmonary sequestration in children: a retrospective study of 58 patients.

Background: Identifying the blood supply from a systemic artery is crucial for diagnosing extralobar pulmonary sequestration. Contrast-enhanced computed tomography (CT) can accurately delineate the origin and course of anomalous systemic arteries and venous drainage. However, it remains challenging to make an accurate diagnosis in cases with atypical CT manifestations.

Objective: To improve our understanding of the diversity of extralobar pulmonary sequestration and facilitate a more accurate diagnosis, especially for cases with atypical CT manifestations.

Materials and methods: A retrospective review was conducted on 58 patients who had confirmed extralobar pulmonary sequestration by surgery between November 2019 and December 2023. Patient demographics, clinical manifestations, and CT findings were reviewed.

Results: Among the 58 patients, 38 (65.5%) were male, and the left-to-right ratio was 47 to 11. It typically appeared triangular or polygonal, with the sharp angular sign observed in 55 patients (94.8%). The low-density branch sign was identified in 45 patients (77.6%) via contrast-enhanced CT. Lesions were located as follows: above the diaphragm in 45 cases (77.6%), within the diaphragm in seven cases (12.1%), and below the diaphragm in two cases (3.4%), presenting as solid masses; two instances (3.4%) involved anterior mediastinum lesions that presented as cystic-solid masses. In two cases (3.4%), the sequestered lung communicated with the lower esophagus, presenting as multiple air-filled cystic lesions. Abnormal arterial blood supply was detected in 54 patients (93.1%), whereas venous drainage was identified in 52 patients (89.7%).

Conclusion: The presence of the sharp angular sign in a solid mass with clear boundaries suggests a diagnosis of extralobar pulmonary sequestration on routine CT, regardless of its location above, within, or below the diaphragm. CT angiography is a reliable imaging modality for documenting feeding arteries and draining veins, which confirms the diagnosis of extralobar pulmonary sequestration. The low-density branch sign on contrast-enhanced CT indicates that the lesion comprises lung tissue and helps establish a diagnosis of pulmonary sequestration.