Characteristics of Intralobar Pulmonary Sequestration
Intralobar pulmonary sequestration is characterized by abnormal lung tissue that receives its arterial blood supply from the systemic circulation, typically the aorta, and has venous drainage through the pulmonary veins rather than the azygos system. 1, 2
Vascular Supply and Drainage
- Intralobar pulmonary sequestration is supplied by systemic arterial circulation, most commonly from the descending thoracic aorta (74% of cases) 3
- Some cases may have multiple feeding vessels from different origins, such as the arcus aorta and celiac trunk 3
- The venous drainage of intralobar pulmonary sequestration occurs through the pulmonary venous system rather than the azygos venous system 2, 4
- The feeding vessels can sometimes become aneurysmal, posing a risk for life-threatening hemorrhage if not properly controlled during surgical management 2
Anatomical Characteristics
- Intralobar pulmonary sequestration is contained within the normal lung tissue and shares the same pleural covering as the adjacent normal lung (does not have a separate pleural covering) 4, 5
- It is more common in the left lung and predominantly affects the lower lobes (60-90% of cases) 5
- The sequestered lung tissue does not communicate with the normal tracheobronchial tree 6
- Intralobar sequestration represents approximately 75% of all pulmonary sequestrations, with extralobar sequestration accounting for the remaining 25% 5
Associated Conditions
- Unlike extralobar sequestration, intralobar pulmonary sequestration is not commonly associated with diaphragmatic defects 4, 5
- It is characterized as abnormal lung tissue of embryonic origin that failed to develop normal connections with the tracheobronchial tree 4
- Recurrent pneumonia and hemoptysis are common complications associated with intralobar pulmonary sequestration 6
Diagnostic Imaging
- CT angiography is excellent for defining the anomalous vascular supply and drainage patterns of pulmonary sequestrations 1
- MRI can be useful for delineating the vasculature of pulmonary sequestrations when contrast-enhanced CT is contraindicated 2
- Diagnostic imaging should evaluate both the arterial supply from the systemic circulation and confirm venous drainage through the pulmonary veins 4, 6
Treatment Options
- Surgical resection (lobectomy or sublobar resection) is the traditional treatment for intralobar pulmonary sequestration 5
- Video-assisted thoracoscopic surgery (VATS) has emerged as a minimally invasive approach with benefits of early discharge and lower complication rates 5
- Preoperative embolization of the feeding systemic vessels may facilitate safer VATS resection by reducing the risk of intraoperative hemorrhage 4
- Endovascular embolization alone has been reported as a less invasive management option in selected cases, particularly for patients with complications like hemoptysis 6
Based on the available evidence, intralobar pulmonary sequestration is supplied by the aorta (option a is correct), drains through the pulmonary venous system rather than the azygos system (option b is incorrect), is not commonly associated with diaphragmatic defects (option c is incorrect), and shares the same pleural covering as the adjacent normal lung rather than having a separate pleural covering (option d is incorrect).