Disorganizing-fibrosing processes in alveolar walls of interstitial pneumonia, "alveolopneumonitis": a morphopathological study.

Disorganizing-fibrosing processes of alveolar walls in 13 autopsied (including 4 previously biopsied) and 3 biopsied cases of acute and chronic interstitial pneumonia were presented. The processes of alveolar walls were characterized initially by histolysis of the alveolar walls and transformation of the tissue into mesh or reticular structure caused by proliferation of fixed cells probably of endothelial cell origin, subsequently by formation of basement membrane-like structures along the proliferated cells, and ultimately by either fibrosis of the entire thickness of the disorganized tissue or axial fibrosis with accumulation of proliferated cells towards axis and peripheral recanalization. These processes tended to occur in the subpleural regions and extend thereafter to the deeper portions of lungs. In some cases recurrent alveolitis which occurred on the basis of axial fibrosis as aforementioned was noted. Problems concerning genesis and nature of these processes were discussed, and a new nomenclature "alveolopneumonitis" was proposed instead of interstitial pneumonia.