Correlation between the SP-A positive ratio and FF score in UIP patients. SP-A positive ratio = number of SP-A positive epithelial cells/total number of alveolar epithelial cells in studied areas × 100. FF scores indicate the number of fibroblastic foci within a lower-power magnification field.
Nagata et al. Diagnostic Pathology 2011 6:25 doi:10.1186/1746-1596-6-25