PULMONARY SEQUESTRATION
 
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PULMONARY SEQUESTRATION

 

DEFINITION:

A congenital anomaly of the lung characterized by cystic, non-functioning pulmonary tissue nourished by systemic arteries.

EPIDEMIOLOGY:

  • incidence: ?
  • age of onset:
    • depends on type
  • risk factors:
    • see types

PATHOGENESIS:

1. Background

  • represents a malformation of the primitive respiratory and vascular systems in which fetal lung tissue is segregated from the main tracheobronchial apparatus and ultimately has its own systemic artery
  • the etiology of the embryologic malformation is controversial
    • primary vascular separation
    • primary pulmonary separation
  • the sequestration spectrum includes all anomalies characterized by abnormal connections of one or more of the 4 major components of the lung:
  • 1. tracheobronchial airways - +/- connected
  • 2. lung tissue - disorganized, cystic, fetal
  • 3. arterial supply - systemic
  • 4. venous drainage - systemic

    (diagnostic imaging studies should try to identify each of these components)

    • 2. Types

    1. Intralobar

    • sequestration contained within the visceral pleura
    • M = F
    • slight left-sided predominance
    • usually found in the posterior basal segment of a lower lobe
    • rarely associated with other congenital anomalies
    • arterial supply from the thoracic or abdominal aorta in
    • 75% of cases
    • venous drainage into the pulmonary vein
    • more than ½ of cases diagnosed after adolescence

    2. Extralobar

    • sequestration has own pleura (i.e., accessory lung)
    • M > F (4:1)
    • 90% left-sided
    • usually found between the diaphragm and the lower lobe
    • associated with other congenital anomalies (50%)
      • congenital diaphragmatic hernia
      • communication with esophagus or stomach
      • lymphangectasia
    • arterial supply the same as in the intralobar type
    • venous drainage into the azygos or hemiazygos
    • less common of the 2 types

    CLINICAL FEATURES:

    1. Intralobar

    1. Recurrent Pulmonary Infections

    • secondary to a fistula between the sequestration and either the airway or digestive tract

    2. Complications

    • systemic - chills, fever, weight loss
    • respiratory - chronic cough, hemoptysis, hemothorax, pleural effusion, pyoptosis, abscess
    • cardiovascular - congestive heart failure (due to vascular shunting)

    2. Extralobar

    1. Asymptomatic

    • usually found as a thoracic mass on x-ray
    • greater than 50% of cases are diagnosed before age 1 year

    2. Complications

    • respiratory - abscess formation, TB, infection is uncommon unless a gastrointestinal tract communication

    INVESTIGATIONS:

    1. Imaging Studies

    1. Chest X-Ray

    • large, hemithorax, hyperlucent (bubbly), or opaque
    • extralobar - triangular-shaped densities in the costophrenic angle

    2. Bronchography

    • periphery is outlined by bronchi that are filled with dye (the sequestration is not filled)

    3. Aortography

    • delineates anomalous arterial supply

    4. CT/MRI

    • solid or fluid components with emphysematous lungs
    • basal lesion supplied by a systemic artery

    2. Pathology

    • the pathologic tissue is largely fetal, profusely cystic, and contains disorganized, airless, nonpigmented alveoli, bronchi, cartilage, respiratory epithelium and a systemic artery
    • it isoften secondarily infected, bronchiectatic, or atelectatic

    MANAGEMENT:

    1. Supportive

    • respiratory distress - ventilation
    • infections - antibiotics

    2. Surgery

    • lobectomy

     

     

     

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