Scanning electron microscopic studies on acute interstitial pneumonitis.

Scanning and transmission electron microscopic studies on two autopsy cases of acute interstitial pneumonitis caused probably by anticancer agents and intravenous hyperalimentation were reported. SEM revealed clearly the light microscopic findings of acute interstitial pneumonitis; hyaline membrane, Masson body, and glandular metamorphosis. Additionally an organization-process of Masson body and the relationship between Masson body and hyaline membrane were shown by SEM. TEM revealed three kinds of myelin-like lamellate structures in the alveolar exudates of both cases, and they were associated with the lamellar body of the B (type II) alveolar epithelium and the secretory granules of Clara-like cell. The myelin-like lamellate structures might suggest the degree of alveolar damage.