What are the characteristics of pulmonary sequestration?

Characteristics of Pulmonary Sequestration

Pulmonary sequestration is characterized by extralobar sequestration being supplied by the aorta (option C is correct), while intralobar sequestration drains into pulmonary veins (option E is incorrect). The other options are also incorrect.

Definition and Types

Pulmonary sequestration is a rare congenital malformation consisting of nonfunctioning pulmonary tissue that lacks normal communication with the bronchial tree and is supplied by a nonpulmonary systemic artery.

There are two distinct types:

1. Intralobar Sequestration (ILS):

   • More common (approximately 75-90% of cases) 1
   • Located within the normal lung parenchyma without its own pleural covering
   • Arterial supply: Systemic arteries (typically from the thoracic or abdominal aorta)
   • Venous drainage: Pulmonary veins to the left atrium 2

2. Extralobar Sequestration (ELS):

   • Less common (approximately 10-25% of cases) 1
   • Has its own pleural covering, separate from normal lung
   • Arterial supply: Systemic arteries (typically from the aorta) 2
   • Venous drainage: Systemic veins (typically azygos or hemiazygos system)

Location

• Pulmonary sequestration predominantly occurs on the left side (option A is incorrect)
• Left lower lobe involvement is approximately 2.1 times more frequent than right lower lobe 3
• Extralobar sequestration is typically located at the base of the lung (71%) or between lobes (29%) 1

Vascular Supply and Drainage

• Intralobar sequestration:

  • Arterial supply: Systemic arteries (NOT pulmonary artery - option B is incorrect)
  • Venous drainage: Pulmonary veins (NOT systemic veins - option D is incorrect)

• Extralobar sequestration:

  • Arterial supply: Systemic arteries (typically from the aorta - option C is correct)
  • Venous drainage: Systemic veins

Diagnostic Imaging

• CT angiography (CTA) is the preferred diagnostic modality, though it only identifies the condition in about 37.5% of cases prior to surgery 3
• MR angiography (MRA) is useful for detailed delineation of vascular anatomy without radiation exposure
• Key imaging findings include:
  • Soft tissue opacity
  • Cystic lesions
  • Cavitary lesions
  • Bronchiectasis 3

Clinical Presentation

• Recurrent respiratory infections in the same anatomic location
• Hemoptysis
• Cough and expectoration
• Chest pain
• Fever

Treatment Options

• Surgical resection (lobectomy in 46% of cases, segmental resection in 30%) 1
• Endovascular embolization of feeding vessels is an emerging alternative to surgery in selected cases 4, 5

Complications

• Recurrent infections
• Hemoptysis
• Pulmonary aspergillosis (found in 9.7% of adult cases) 3
• Pseudomonas aeruginosa is the most common bacterial pathogen 3

Pulmonary sequestration represents a spectrum of congenital lung anomalies with distinct vascular patterns that are critical for proper diagnosis and management.