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 obser vations show that the alveolar epithelial cells, endothelial cells and basement membrane are all injured, interstitial macrophages hyperpplasia, mast cells infiltration and degranulation, electron dense deposits at alveolar wall are present. These morphologic changes provide basis for formation of idiopathic pulmonary fibrosis.