Birefringent particles as an effective factor in usual interstitial pneumonia

Background: It has long been recognized that birefringent paticles (BP) are associated with pulmonary disease. And there is increasing evidence that BP cause fibrotic reaction within the lung depending on both particle size and composition. Methods: We collected 41 cases of usual interstitial pneumonia (UIP) and 101 cases of normal lung tissue from control group including squamous cell carcinoma, adenocarcinoma and bullae. BPs in the 0:1 to 10 μm size range under polarizing microscope was measured and counted by image analyzer. Results: BP counts are mean 244.05/10 HPF in UIP and 71.4/10 HPF in control group. BPs in UIP is three times more than control (p=0.000). It increased significantly by the age of patients (p=0.000). Conclusions: BPs in lung might be important cause of inflammation and fibrosis in UIP.