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