ACUTE AND CHRONIC HUMAN ADENOVIRUS PNEUMONIA - CELLULAR AND EXTRACELLULAR-MATRIX COMPONENTS

We present a comparative histopathological study of both acute and chr onic human adenovirus pneumonia, with reference to the cellular and ex tracellular matrix components. Seventeen lungs from autopsied patients whose ages ranged from 2 to 60 months were studied. Adenovirus types 1, 2, 3, 5, and 7 were isolated from 15 patients with acute lung disea se, and types 2 and 7 were isolated from the other two patients with c hronic pulmonary illness. The results indicated the occurrence of two basic patterns of adenovirus interstitial pneumonia: (1) classic patte rn (acute), characterized by necrosis and degeneration and many type I I pneumocytes with intranuclear inclusion bodies, which were positive for adenovirus DNA by in situ hybridization,and (2) proliferative or p roliferative-productive pattern (chronic), which presented with diffus e pulmonary fibrosis and the interstitial proliferation of fibroblast- like cells, compatible with myofibroblasts (positive for vimentin and alpha smooth muscle actin), and increase in collagen types I and III, elastic fibers, and proteoglycans. Alveolar collapse appears to be an important pathogenetic mechanism in the development of this pattern.