Emphysema – morphology

EMPHYSEMA – MORPHOLOGY
  • Definition – Abnormal permanent dilatation of air spaces distal to the terminal bronchioles along with destruction of the walls of dilated air spaces without obvious fibrosis
  • Gross :
    • Lungs – Voluminous, pale with little blood
    • Mild cases – Dilatation of airspace   
    • Advanced – Subpleural bullae and  blebs  
    • Bullae Air filled cystic structures  > 1 cm 
    • Blebs – Rupture of alveoli directly into subpleural interstitial tissue
  • Depending upon the anatomic distribution within lobule emphysema is classified into
    • Centriacinar (Centrilobular)
    • Panacinar (Panlobular)
    • Paraseptal (Distal acinar)
    • Irregular          (Para – Cicatrical)
    • Mixed (Unclassified)   
  • CENTRIACINAR EMPHYSEMA
    • Involvement of central or proximal part of the acinus where as distal part is spared
    • Usually co-exists with chronic bronchitis
    • Predominant in smokers /  coalminers pneumoconiosis
    • Morphology-
      • Gross : Common in upper lobes of lungs
      • C/S : Distended air spaces in centre of lobules surrounded by a rim of normal lung parenchyma
    • Microscopy :
      • Distension & destruction of respiratory bronchiole & narrowing of terminal bronchiole
  • PANACINAR EMPHYSEMA
    • All portions of the acinus are affected
    • Often associated with α1-AT  deficiency in  smokers
    • Gross :
      • Common in lower zone of lungs
      • Enlarged & over inflated lungs
    • Microscopic examination :
      • All portions of acini are distended with thin & stretched alveolar walls
      • Spurs of broken septa due to rupture of  alveolar walls
    • Special stains :  Loss of elastic tissue
  • PARASEPTAL (DISTAL) EMPHYSEMA
    • Involves only distal part of acinus whereas proximal part is normal
    • Localised along the pleura & perilobular septa
    • More severe in the upper half of the lungs
    • Common cause of spontaneous pneumothorax in young adults
  • IRREGULAR (PARA-CICATRICAL) EMPHYSEMA
    • Seen surrounding scars from any cause
    • Irregular involvement
    • Usually asymptomatic
    • May be incidental autopsy  finding
  • MIXED EMPHYSEMA
    • Usually occurs in severe cases
    • Mixture of Centriacinar in upper lobes, Panacinar in lower lobes & Paraseptal in subpleural region
Types of emphysema
Reference 
  1. Vinay kumar, Abul K.Abbas, Nelson Fausto, Jon C. Aster. Robbins and Cotran Pathologic basis of disease. 8th edition.