Basic fibroblast growth factor expression in recurrent versus non-recurrent nasal polyposis.

Various growth factors are expressed in nasal polyps, and some of these have been suggested to play a role in polyp formation. A potential relation between growth factor expression and polyp recurrence, however, is undetermined. Basic fibroblast growth factor (bFGF) is expressed in mononuclear cells, as well as in endothelial and epithelial surface and gland cells of nasal polyps. To determine whether bFGF may play a role in the recurrence of nasal polyps, the present study aimed at a comparison of bFGF expression in recurrent versus non-recurrent polyps. Further, the expression in polyps from asthmatic patients was compared with that from non-asthmatics. Thirty patients with newly diagnosed nasal polyposis were included. Polypectomy was performed at entry to the long-term follow-up study. Fifteen patients only had one polypectomy (no recurrence group, with a median observation time of 81 months). Fifteen patients had a median of 6.4 polypectomies (multiple recurrence group, with a median observation time of 108 months). Five of nine patients with asthma belonged to the non-recurrence group and four to the recurrence group. The polyp from the entrance polypectomy was examined for expression of bFGF by immunohistochemistry, using a polyclonal antibody. A masked semi-quantification of staining intensity was performed in recurrent versus non-recurrent polyps, as well as in asthmatics versus non-asthmatics. bFGF expression was seen as varying staining of the polyp surface and gland epithelium, as well as of some mononuclear cells and some fibroblast-like cell profiles in the polyp stroma. Vascular endothelium was labeled occasionally. Semi-quantification of the staining intensity showed no significant differences between recurrent and non-recurrent polyps, or between asthmatics and non-asthmatics. We conclude that the level of immunohistochemical expression of bFGF in recurrent and non-recurrent nasal polyposis is equivalent. Thus, the level of bFGF expression in the primary polyp can not predict a subsequent recurrence. The expression of bFGF is not up-regulated in patients with asthma. Further studies are needed to determine a potential role of bFGF in nasal polyposis, with special reference to different stages of polyp formation and growth.