Characteristics of Extralobar Pulmonary Sequestration
Extralobar pulmonary sequestration is characterized by being supplied by the aorta, having its own pleural covering, typically not connected to the bronchial tree, more commonly found on the left side, and rarely presenting with recurrent pulmonary infections.
Anatomical Features
- Extralobar pulmonary sequestration is a rare congenital anomaly consisting of non-functioning pulmonary tissue that is anatomically separate from the normal lung 1
- It has its own visceral pleura that is not continuous with normal lung tissue, unlike intralobar sequestration which shares a common pleura with normal parenchyma 2
- The blood supply is derived from systemic vessels, typically branches from the aorta 1, 2
- The venous drainage is typically through the systemic circulation (azygos, hemiazygos, or portal veins), NOT through the pulmonary veins 2
- Extralobar sequestrations are more commonly found on the left side and in the lower hemithorax (60-90%) 3, 4
Clinical Presentation
- Unlike intralobar sequestration, extralobar sequestration typically does NOT present with recurrent pulmonary infections due to the absence of a connection to the tracheobronchial tree 2
- It typically manifests in the newborn period or early infancy with symptoms of respiratory distress 1
- Less frequently, patients present in childhood or adulthood, often as an incidental asymptomatic finding 1, 2
- When symptomatic, it may manifest as hypoxia, cardiac failure, or rarely, torsion of the sequestrum 2
Diagnostic Features
- Radiologically, extralobar sequestration typically appears as a homogeneous soft-tissue mass in the lower hemithorax 1
- These lesions can also occur in the mediastinum, within the diaphragm, and rarely, below the diaphragm 1, 2
- CT angiography is recommended for defining the anomalous vascular supply and drainage patterns 5
- Contrast-enhanced CT is indicated when there is suspicion of vascular abnormalities such as pulmonary sequestration 5
- Diagnosis relies on identification of the systemic vascular supply, which can be demonstrated through angiography, ultrasound, CT, or MRI 1
Management
- Treatment of extralobar sequestration consists of surgical excision of the mass 1
- The primary reasons for resection are to prevent hemorrhage or malignant transformation of the tissue 2
- Minimally invasive techniques such as video-assisted thoracoscopic surgery (VATS) can be used, allowing for early discharge and a low rate of complications 3
- Prognosis is usually favorable in the absence of associated congenital anomalies 1
Key Differences from Intralobar Sequestration
- Intralobar sequestration shares a common pleura with normal lung parenchyma, while extralobar has its own pleural covering 2
- Intralobar sequestration typically presents with recurrent infections, while extralobar sequestration usually does not 2, 6
- Intralobar sequestration is more common (75% of cases) than extralobar sequestration (25% of cases) 3