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 – Involvement of central or proximal part of the acinus where as distal part is spared
Panacinar (Panlobular) – All portions of the acinus are affected
Paraseptal (Distal acinar) – Involves only distal part of acinus whereas proximal part is normal
Irregular (Para – Cicatrical) – Seen surrounding scars from any cause and has irregular involvement
Mixed (Unclassified) – 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