Prognostic Value of Fibroblastic Foci in Patients with Usual Interstitial Pneumonia

Park, Yong Bum; Kang, Gil Hyun; Kitaichi, Masanori; Shim, Mae Sun; Lim, Chae Man; Lee, Sang Do; Koh, Youn Suck; Kim, Woo Sung; Kim, Won Dong; Kim, Dong Soon

Abstract

BACKGROUND: Usual interstitial pneumonia (UIP) is a progressive disorder characterized by a poor response to conventional immunosuppressive agents and significant mortality. The histologic hallmark of UIP is patchy subpleural fibrosis with interposed fibroblastic foci(FBF) and relatively normal appearing lung. FBF is a collection of actively proliferating myofibroblasts, which may represent the activity of IPF. However, there were contradictory reports about the correlation between the degree of FBF and survival. The objective of this study was to investigate the roles of FBF as prognostic marker of UIP. METHOD: This was a retrospective study on the 46 patients(M:F=33:13, mean age:59+/-12 years) who had the surgical lung biopsy done at the Asan Medical Center, Seoul, Korea between 1990 and 2000 and had follow-up of more than a year. All the biopsy specimens were reevaluated and diagnosed as UIP according to the new classification. Semiquantitative grading of FBF(absent, 0; mild 1; moderate 2; marked 3) was performed by the experienced pathologists and compared to the clinical data and the follow up course. RESULTS: Thirteen patients(28.2%) died of UIP progression during the study period. The median survival time of all the subjects was 26 months after the biopsy. The FVC, DLco, smoking history and the grade of FBF were significantly related to the risk of death. The survival was longer in subjects with lesser degrees of FBF, higher DLco, higher FVC and history of smoking .The multivariate analysis with Cox regression test showed the extent of FBF was the only independent prognostic marker of UIP. CONCLUSION: These data suggested that the extent of FBF on the surgical lung biopsy can be used as a prognostic marker of UIP.