Histologic Changes

This airway shows little inflammation. At the top and to the right, it is normal, but at the left it shows the development of subepithelial scar (SS) of early cicatricial, constrictive bronchiolitis. The overlying epithelium shows focal lymphoid infiltrates and erosions (arrows). The tall columnar epithelium adjacent to the focal erosions produces an "up-down" pattern. The bronchiolar smooth muscle (SM) next to the scar appears slightly thickened. The pulmonary artery lies to the right.

This elastic-van Gieson stain of a similar airway shows that the elastic layer that normally hugs the epithelium (upper arrow) is separated from the epithelium at the lower right (lower arrow) by pink staining (van Gieson positive), cellular, collagenous tissue, which is not yet dense scar. Note that the epithelium over the scar shows focal erosion. Again, smooth muscle (SM) appears thickened adjacent to the scar.

Clinical summary Image 4

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