<prompt> Which of the following is due to chronic smoking:Centri-acinar emphysemaPanacinar emphysemaIrregular emphysemaMixed variety  <response>: Ans. a Centri-acinar emphysemaRef: Harrison 18th edition, Chapter 13 Centri-acinar lesions are more common and severe in the upper lobes, particularly in the apical segments. In severe centriacinar emphysema the distal acinus also becomes involved, and so, as noted, the differentiation from panacinar emphysema becomes difficult. This type of emphysema is most commonly seen as a consequence of cigarette smoking in people who do not have congenital deficiency of aantitrypsin. 