An investigation of the giant cell fibroma

Abstract

The giant cell fibroma is a reactive fibrous overgrowth of the oral mucosa characterised by the presence of bizarre large stellate mononuclear and multinuclear cells in the lamina propria. Since this lesion had never been reported in Malta, the pathology archives at St Luke's Hospital were searched for possible cases of giant cell fibroma and data on the incidence of this lesion were tabulated and compared with those reported in the literature.

Immunohistochemistry was carried out on material retrieved from the pathology archives and identified as cases of giant cell fibroma in order to ascertain the phenotype of the cells which characterize this lesion. The phenotype of these cells was compared to that of histologically similar cells found in the cervix, in fibrous papules of the nose (face) and in one case of allergic nasal polyps. It was concluded that the characteristic cells of the giant cell fibroma and histologically similar cells in fibrous papules of the nose (face) and frequently in the cervix are fibroblasts whilst a subset of similar cells in the cervix and in allergic nasal polyps are myofibroblasts.

The expression of the cell proliferation markers Ki67 and proliferating cell nuclear antigen was also investigated in order to test the hypothesis that mutinucleation of the stellate cells is being caused by cell division in the absence of kinesis. Since two reports by previous authors mention that in several lesions and anatomical sites mast cells were noted to be in contact with the large stellate cells, the presence and location of mast cells in giant cell fibromas, cervix, fibrous papules of the nose (face) and in the case of allergic nasal polyps were investigated. It was concluded that the cells under study in all sites and lesions studied are not cycling and that therefore multinucleation is probably achieved by the fusion of mononuclear cells. Furthermore, very few stellate cells were seen to be in contact with or in the immediate vicinity of a mast cell, and so it is unlikely that mast cells are inducing multinucleation in the stellate cells.

The final part of this study consisted of the comparison of the distribution of various components of the extracellular matrix of giant cell fibromas, fibrous polyps and epulides of the oral mucosa and denture related fibrous overgrowths in order to ascertain whether any differences exist between giant cell fibromas and other reactive fibrous overgrowths of the oral mucosa. It was concluded that no significant differences between these lesions exist and that these lesions probably form part of the same disease process. Because of this and because of the fact that the atypical stellate cells which characterize the giant cell fibroma are not unique to this lesion but are in fact widely-distributed in many lesions and even in normal mucosa in various anatomical sites, it is proposed that the giant cell fibroma should not he separated out as a discrete disease entity hut should he described as a reactive fibrous polyp or epulis containing large stellate fibroblasts.