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