Scanning electron microscopic observations of emphysema in humans. A descriptive study.

We have performed dissecting light and scanning electron microscopy (SEM) on 14 lungs with mild centrilobular emphysema, two of which also had mild panacinar emphysema. The lungs were surgically resected, mainly for cancer. The walls of centrilobular emphysema were either thick or thin. The former were less common and represented fibrosis of the walls. The latter were less fibrotic, but some fibrosis was seen. Adjacent alveoli were compressed and distorted, and overlapping walls of air spaces occurred. In panacinar emphysema alveolar ducts were enlarged and flattened with transverse linear bands interpreted as flattened walls of enlarged alveoli. The walls of air spaces were chiefly lined by type I and type II epithelial cells, but occasionally bronchiolar epithelium lined the proximal emphysematous spaces. Supplying bronchioles showed diminished numbers of ciliated cells with cilia of reduced height. SEM was much more sensitive than dissecting microscopy in recognizing emphysema. The apparent fibrosis suggests that the definition of emphysema may have to be reconsidered and that if fibrosis is apparent, the proteolysis-antiproteolysis hypothesis of the pathogenesis of emphysema may have to be modified.