Learning Radiology xray montage
 
 
 
 
 

Bronchpulmonary Sequestration
Submitted by Samir Jethra, MSIV


Bronchopulmonary Sequestration

  • Bronchopulmonary sequestration (BPS) is a rare congenital malformation of the
    lower respiratory tract.
  • It consists of a nonfunctioning mass of normal lung tissue that lacks normal
    communication with the tracheobronchial tree, and that receives its arterial blood
    supply from the systemic circulation.
  • BPS is estimated to comprise 0.15 to 6.4 percent of all congenital
    pulmonary malformations, making it an extremely rare disorder.
  • Sequestrations are classified anatomically.
    • Intralobar sequestration (ILS) in which the lesion is located within a
      normal lobe and lacks its own visceral pleura.
    • Extralobar sequestration (ELS) in which the mass is located outside the
      normal lung and has its own visceral pleura
  • The blood supply of 75% of pulmonary sequestrations is derived from
    the thoracic or abdominal aorta.
    • The remaining 25% of sequestrations receive their blood flow from
      the subclavian, intercostal, pulmonary, pericardiophrenic, innominate,
      internal mammary, celiac, splenic, or renal arteries.

Intralobar sequestration

  • The intralobar variety accounts for 75 percent of all sequestrations.
  • Usually presents in adolescence or adulthood as recurrent pneumonias.
  • Lies within the same visceral pleura as the lobe in which it occurs.
  • Males and females are equally affected with ILS.
  • In ILS, the arterial supply usually is derived from the lower thoracic or
    upper abdominal aorta.
  • Venous drainage is usually to the left atrium via pulmonary veins establishing
    a left to right shunt.
    • Abnormal connections to the vena cava, azygous vein, or right atrium may occur.
  • Two thirds of the time, the sequestration is located in the paravertebral
    gutter in the posterior segment of the left lower lobe.
  • Unlike extralobar sequestration, it is rarely associated with other
    developmental abnormalities.
  • Patients present with signs and symptoms of pulmonary infection of a lower lobe mass.
    • It is believed that sequestrations become infected when bacteria
      migrate through the pores of Kohn or if the sequestration is incomplete.

Extralobar sequestration

  • The extralobar variety accounts for 25 percent of all sequestrations.
  • ELS usually presents in infancy with respiratory compromise.
  • Develops as an accessory lung contained within its own pleura.
  • ELS has a male predominance (80%).
  • Related to the left hemidiaphragm in 90% of cases.
    • ELS may present as a subdiaphragmatic or retroperitoneal mass.
  • In general, the arterial supply of ELS comes from an aberrant vessel arising from the thoracic aorta.
  • It usually drains via the systemic venous system to the right atrium, vena cava, or azygous systems.
  • Congenital anomalies occur more frequently in patients with ELS than ILS.
    • Associated anomalies include Congenital cystic adenomatoid malformation (CCAM), congenital diaphragmatic hernia, vertebral anomalies, congenital
      heart disease, pulmonary hypoplasia, and colonic duplication
  • Since it is enveloped in its own pleural sac, it rarely gets infected so
    almost always presents as a homogeneous soft tissue mass.
  • The mass may be closely associated with the esophagus, and fistulae may develop.

Imaging

  • An arteriogram has been considered vital in documenting the systemic
    blood supply, allowing definitive diagnosis as well as preoperative planning.
  • The advent of new noninvasive imaging techniques has changed this thinking.

CHEST RADIOGRAPH

  • Sequestrations typically appear as a uniformly dense mass within the thoracic
    cavity or pulmonary parenchyma.
  • Recurrent infection can lead to the development of cystic areas within the mass.
  • Air-fluid levels due to bronchial communication can be seen.

ULTRASOUND

  • The typical sonographic appearance of BPS is an echogenic homogeneous
    mass that may be well defined or irregular.
  • Some lesions have a cystic or more complex appearance.
  • Doppler studies are helpful to identify the characteristic aberrant systemic
    artery that arises from the aorta and to delineate venous drainage.

CT

MRI

 

 

Intralobar Sequestration, Right Lower Lobe. There is a mass in the right lower lobe (white arrows) which is drawing its blood supply (red arrows) from the descending aorta. Drainage was back to the pulmonary veins.

Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging, 4th ed., 2001 Churchill Livingstone, Inc. pp 654-655. 

Khan, Ali Nawaz, Bronchopulmonary Sequestriation, e-Medicine, http://www.emedicine.com/radio/topic585.htm.  

Oermann, Christopher M, Bronchopulmonary Sequestration, Up to Date, http://www.utdol.com/application/topic.asp?file=pedipulm/10425&type=P&selectedTitle=4~6