What are the types, clinical presentation, diagnostic work‑up, and management options for pulmonary sequestration?

Pulmonary Sequestration: Comprehensive Overview

Definition and Classification

Pulmonary sequestration is a congenital bronchopulmonary malformation consisting of nonfunctioning lung tissue that lacks normal communication with the tracheobronchial tree and receives arterial blood supply from systemic vessels rather than the pulmonary circulation. 1

Two Main Types:

Intralobar Sequestration (ILS):

• Shares the pleural envelope with normal lung tissue 1
• Accounts for approximately 73% of all sequestrations 2
• More commonly presents in adults 2
• Typically located in the posterior basal segments of the lower lobes 1

Extralobar Sequestration (ELS):

• Has its own separate pleural covering 1
• Represents approximately 27% of cases 2
• Approximately 90% occur in the left hemithorax 3
• Can be located below the diaphragm in approximately 10% of cases 3
• More commonly diagnosed in infancy or prenatally 4

Vascular Anatomy

Arterial Supply:

• 80% receive blood from a direct branch of the thoracic or abdominal aorta 3
• 15% supplied by another systemic artery 3
• 5% receive blood from the pulmonary artery 3

Venous Drainage:

• ELS drains predominantly into systemic circulation via azygos vein, hemiazygos vein, or inferior vena cava 3
• Approximately 25% drain completely or partially through pulmonary veins 3
• Rare cases may drain into the portal vein 3

Clinical Presentation

Intralobar Sequestration:

• May remain asymptomatic until adulthood 5
• Recurrent pneumonia or lung infections in the same location 2, 5
• Chronic cough and recurrent respiratory infections since childhood 5
• Hemoptysis (mild to moderate) 6
• May mimic difficult-to-treat asthma with frequent exacerbations 5
• Chest pain 1

Extralobar Sequestration:

• Often diagnosed prenatally or in infancy 4
• Usually asymptomatic unless complicated 4
• May present with respiratory distress if large 7

Fetal Presentation:

• Large bronchopulmonary sequestrations can cause mediastinal shift, impaired venous return, and esophageal compression leading to polyhydramnios 7
• Nonimmune hydrops fetalis occurs in approximately 5% of cases with large lesions, conferring poor prognosis without treatment 7
• Pulmonary sequestration has a more favorable natural history with frequent spontaneous regression compared to congenital pulmonary airway malformation (CPAM). 4

Diagnostic Work-Up

Initial Imaging:

• Chest radiography may show a mass lesion, often in the lower lobes, or recurrent infiltrates in the same location 2
• Radiographic features can be sufficiently suggestive to raise suspicion 2

Definitive Imaging:

• CT angiography is the gold standard for defining the anomalous vascular supply and drainage patterns, as recommended by the American College of Radiology. 8
• CT chest without contrast can identify the mass and anatomical abnormalities 9
• Contrast-enhanced CT or CTA is indicated when vascular abnormalities such as pulmonary sequestration are suspected, particularly for presurgical planning to identify feeding vessels. 9
• Multidetector CT provides powerful diagnostic capability for both diagnosis and treatment planning 1

Angiography:

• Historically used to confirm diagnosis and identify feeding vessels 2
• Now largely replaced by CT angiography 8

Prenatal Diagnosis:

• Ultrasound can identify the lesion and associated complications 7
• Fetal MRI may provide additional anatomical detail 7

Management Options

Prenatal Management:

For Large Lesions with Hydrops:

• Neodymium:yttrium-aluminium-garnet (Nd:YAG) laser ablation of the feeding vessel is recommended by the American College of Obstetricians and Gynecologists for large bronchopulmonary sequestrations causing complications. 7, 4

Expectant Management:

• Sequestrations are managed expectantly unless complicated by hydrothorax, as recommended by the American Academy of Pediatrics. 4
• Serial ultrasound monitoring for spontaneous regression 4

Postnatal/Adult Management:

Surgical Resection:

• Elective resection is typically performed after birth for lesions that do not regress spontaneously. 4
• Lobectomy is the most common procedure (46% of cases) 2
• Segmental resection performed in 30% of cases 2
• Video-assisted thoracoscopic surgery (VATS) is increasingly used for minimally invasive resection 3
• Section-ligature of abnormal feeding vessels is essential during surgery 6

Indications for Surgery:

• Recurrent infections 2, 5
• Hemoptysis 6
• Symptomatic lesions 5
• Persistent lesions that do not regress 4
• Prevention of potential complications including infection, hemorrhage, and rare malignant transformation 2

Surgical Outcomes:

• Post-operative morbidity is low 2
• Most significant complications include pleural empyema, hemothorax, and (rarely) hemopneumoperitoneum with extralobar sequestration 2
• Long-term outcomes are highly favorable 2
• No evidence of metaplasia or pre-neoplastic changes in most series 2

Common Pitfalls and Caveats

Diagnostic Pitfalls:

• Misdiagnosis as recurrent pneumonia in the same location—always consider sequestration when infections repeatedly affect the same lung segment 5
• Mimicking asthma with frequent exacerbations—obtain CT imaging if asthma is difficult to control with recurrent infections 5
• Failure to identify feeding vessels preoperatively can lead to unexpected intraoperative hemorrhage—always obtain CT angiography before surgery 8, 9
• In 6 of 26 cases in one series, diagnosis was only made at exploratory thoracotomy due to inadequate preoperative imaging 2

Management Pitfalls:

• Attempting conservative management in symptomatic adults—surgical resection provides definitive treatment with excellent outcomes 2
• Inadequate preoperative vascular mapping—identify all feeding vessels and drainage patterns before surgery 8, 6
• For fetal cases, failing to monitor for spontaneous regression—many lesions regress without intervention 4
• Unnecessary intervention for asymptomatic prenatal sequestrations without hydrops—expectant management is appropriate 4