• Bullae: focal dilation of respiratory air space
    • Usually occur in the setting of diffuse emphysema, but some cases occur with predominantly localized disease
  • Bleb: intrapleural collection of air (these represent a form of interstitial emphysema)
    • Occur in emphysema, newborns, or in adults with ventilator-associated barotrauma
    • May result in pneumothorax or pneumomediastinum
  • Cyst (see Cystic-Cavitary Lung Lesions, [[Cystic-Cavitary Lung Lesions]]): air spaces lined by epithelium (which usually have the characteristics of bronchial epithelium)



  • Mechanisms of Bullae Formation: the bullae may be simple airspaces or may retain the trabeculations of the emphysematous lung
    • Coalescence of Adjacent Areas of Emphysematous Lung
    • Locally Severe Panacinar Emphysema
    • Ball-Valve Effect in Bronchus Supplying an Emphysematous Region of Lung

Clinical Manifestations


  • Most bullae are clinically asymptomatic

Bullitis (Infected Bullae)

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  • Example
    • Clinical History: 82 y/o WM with active tobacco abuse, congestive heart failure, pulmonary hypertension, and home O2-dependent bullous emphysema who was admitted with COPD exacerbation and pneumonia with bullitis (sputum and blood cultures were negative in this case)
    • Radiologic Features
      • Note air-fluid levels within the bullae
      • Note the emphysematous changes in the surrounding right lung, consistent with severe underlying emphysema
      • Also note that the patient had a pre-existing bullae in this location prior to the infection, making the diagnosis of necrotizing pneumonia with cavitation (which can appear similarly) less likely


Increased Risk of Lung Cancer (see Lung Cancer, [[Lung Cancer]])

  • Occurs in presence of giant bullae
  • Most tumors occur in those in the 6th decade of life (although tumors may occur in younger patients with large bullae)


Treatment of Underlying COPD

Treatment of Bullitis

  • Antibiotics
  • Chest Physiotherapy (CPT): to enhance draiange


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