Clinicopathologic study of a series of giant cell fibroma using picrosirius red polarizing microscopy technique.

BACKGROUND Giant cell fibroma (GCF) is a distinct type of fibroma with characteristic large, stellate mononuclear or multinucleated giant fibroblasts; the stroma of GCF is relatively unexplored. The Picrosirus red polarizing microscopy technique is used to characterize the collagen fibers. The aim of this study was to evaluate the staining properties of collagen fibers in GCF and to correlate it with fibroma using Picrosirius red under the polarizing microscope and van Gieson under bright field microscope. METHODS In the present study van Gieson and picrosirius red stained slides of 7 cases each of GCF and fibroma were compared for the staining properties of collagen. Using picrosirus red polarizing microscopy; colors noted in fibroma included yellow, yellowish-orange and green, whereas the GCF showed predominantly yellow and orange colors. In Van Gieson stained sections it was observed that the collagen in GCF was densely packed and arranged perpendicular to the epithelium while the collagen in fibroma was loosely packed and arranged parallel to the epithelium. CONCLUSION   Observable differences in the stroma of the collagen of GCF and fibroma were noted. Collagen in GCF was more mature and dense. The Picrosirius red polarizing technique can be used to assess the collagen in GCF.