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

Reference 

1. Vinay kumar, Abul K.Abbas, Nelson Fausto, Jon C. Aster. Robbins and Cotran Pathologic basis of disease. 8th edition.