[Electron microscopic studies on pathogenesis of idiopathic pulmonary fibrosis].

OBJECTIVE: To observe ultrastructural changes and study the pathogenesis of idiopathic pulmonary fibrosis. METHODS: The clinical manifestations in 9 patients with idiopathic pulmonary fibrosis were selected. Transbronchial lung biopsy materials were obtained for light microscopic and electron microscopic examination. RESULTS: The major morphologic changes were as follows: histologically, alveolar inflammation and interstitial fibrosis were observed. electron microscopic findings were: 1. alveolar type I cells were degenerated, broken-down and desquamated, endothelial cells were swelled, with inter cellular tight junction shortened, alveolar type II cells hyperplastic, basement membrane thinned and deformed; 2. alveolar macrophages and interstitial macrophages were hyperplastic; 3. mast cells were infiltrated and degranulated; 4. electron-dense deposits were present at alveolar wall; 5. myofibroblasts, fibroblasts, collagen and basement membrane like material were hyperplastic. CONCLUSIONS: Electron microscopic observations show that the alveolar epithelial cells, endothelial cells and basement membrane are all injured, interstitial macrophages hyperplasia, mast cells infiltration and degranulation, electron-dense deposits at alveolar wall are present. These morphologic changes provide basis for formation of idiopathic pulmonary fibrosis.