Symptoms vary from mild to severe and radiographs from incidental opacities to an ARDS-like picture. Death can result from IPS or superimposed infection. Wheezes or crackles may be heard on auscultation in about half of patients. The author proposes that early airway lesions may coincide with late parenchymal ones and vice versa. PMNs may be present focally in the interstitium.
Alveolar hemorrhage accompanies the alveolar damage in some cases.
Airway disease consists of a lymphoid infiltrate that invades the airway wall and the epithelium. The epithelium often shows hyperplasia with focal erosions and goblet cell metaplasia. The lumen may have a fibrinopurulent exudate. The interstitial pneumonia, which varies in extent, shows widening of the alveolar walls by a lymphoid infiltrate that occasionally suggests a diagnosis of lymphocytic interstitial pneumonia. There is type II cell hyperplasia, and the cells are often atypical.