Endothelial cell damage and tubuloreticular structures in interstitial lung disease associated with collagen vascular disease and viral pneumonia.

Lung tissue showing the light microscopic changes of interstitial inflammation and fibrosis was studied electron-microscopically in 11 patients with collagen vascular disease and 26 patients with viral pneumonia. All patients exhibited progressive respiratory insufficiency and had abnormal pulmonary function test results. Endothelial cell cytoplasmic swelling and intracellular tubuloreticular structures were the dominant ultrastructural change in the lungs of both groups. Tubuloreticular structures were identified in peripheral blood lymphocytes in all patients with collagen vascular disease and in 2 with viral pneumonia. Tubuloreticular structures were not identified in the lung tissue from various control patients and in the lymphocytes from patients with idiopathic interstitial pulmonary fibrosis. We conclude that (1) the ultrastructural changes seen in viral pneumonia and collagen vascular-associated interstitial lung disease are essentially identical; (2) endothelial cell damage may be the primary pathologic change associated with both diseases; (3) tubuloreticular structures are seen in large numbers in lung tissue from patients with viral pneumonia and collagen vascular disease; (4) tubuloreticular structures are present in peripheral blood lymphocytes from all patients with collagen vascular disease.