On cut section of the lung, the dilated airspaces with
emphysema are seen. Although there tends to be some scarring with time
because of superimposed infections, the emphysematous process is one of
loss of lung parenchyma, not fibrosis.
There are two major types of
emphysema: centrilobular (centriacinar) and panlobular (panacinar). The
former involves primarily the upper lobes while the latter involves all
lung fields, particularly the bases. Centrilobular emphysema occurs with
loss of the respiratory bronchioles in the proximal portion of the acinus,
with sparing of distal alveoli. This pattern is most typical for
smokers.Panacinar emphysema occurs with loss of all portions of the acinus
from the respiratory bronchiole to the alveoli. This pattern is typical
for alpha-1-antitrypsin deficiency.
Microscopically at high magnification, the loss of
alveolar walls with emphysema is demonstrated. Remaining airspaces are
dilated.
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