Phenotypic characterisation of stellate and giant cells in giant cell fibroma by immunocytochemistry.

The origin of the stromal, stellate and multinucleate cells in oral giant cell fibroma is unclear. Sixteen giant cell fibromas were stained immunocytochemically for keratin (MNF 116), vimentin, S-100 protein, neurofilaments, glial fibrillary acidic protein, alpha-smooth muscle actin, desmin, CD31 (PECAM-1), CD68, Factor XIIIa and prolyl 4-hydroxylase (5B5). In all cases positive staining was found with vimentin and prolyl 4-hydroxylase, indicating a functional fibroblast phenotype. Reactivity for Factor XIIIa was seen in two cases and in only one was a small number of giant cells stained, suggesting that the majority of oral giant cell fibromas are unrelated to the histologically similar fibrous papule of the nose or facial angiofibroma.