Hereditary gingival fibromatosis and expression of Ki-67 antigen: a case report

BACKGROUND: Hereditary gingival fibromatosis (HGF) is a fibrotic enlargement of the gingiva. The mechanism that leads to the accumulation of abnormal amounts of gingival tissue in HGF is still unknown. The aim of this report was to present the clinical and histopathologic characteristics of a patient with gingival fibromatosis and to evaluate the proliferation of HGF fibroblasts. METHODS: We examined the proliferation rate of fibroblasts in this case by using Ki-67 immunohistochemical staining and compared the rate to fibroblasts of non-fibromatosis gingival tissues from 5 healthy patients serving as controls. RESULTS: There were no Ki-67-positive cells in the lesional tissue, and the control gingiva revealed no immunostaining. The number of Ki-67 antigen-positive epithelial cell nuclei was observed to be low in the basal cell layers of hyperplastic gingival epithelia, similar to the control group. CONCLUSIONS: In the present case, there was no increase in the proliferation rate of lesional fibroblasts observed by Ki-67 immunohistochemical staining as a proliferation marker; only the epithelium was stained. It seems likely that the underlying mechanism of HGF may be an increase in the biosynthesis of collagen and glycosaminoglycans rather than cell proliferation.