Hereditary Gingival Fibromatosis: Report of a Five‐Generation Family Using Cellular Proliferation Analysis

Background: Hereditary gingival fibromatosis (HGF) is an uncommon condition characterized by an accumulation of extracellular matrix resulting in a fibrotic enlargement of the gingiva. The goal of this article is to describe one kindred affected with HGF and discuss the diagnosis, treatment, and control of the disease. The pattern of inheritance, histopathologic characteristics, and proliferative potential of epithelial and mesenchymal cells of HGF are also emphasized. Methods: To characterize the pattern of inheritance and the clinical appearance of gingival overgrowth, 117 family members were examined. The recurrence risk was estimated by the use of a genetic analysis program. Immunohistochemistry against the proliferating cell nuclear antigen (PCNA) and pKi‐67 was performed to assess cellular proliferation of normal gingiva (NG) and HGF cells. Results: Examination of the family pedigree demonstrated an autosomal dominant trait of inheritance, and a sibling recurrence risk of 0.085 and an offspring recurrence risk of 0.078, indicating that HGF was a consequence of genetic alteration with low penetrance. Unaffected and affected members transmitted the disease to their offspring. The affected patients showed a generalized but mild gingival overgrowth. Surgical treatment consisted of a combination of gingivectomy and gingivoplasty. Histologic examination showed that the gingival lesions of all patients were quite similar, with increased amounts of collagen fiber bundles in the connective tissue. Immunohistochemistry revealed that the proliferative potential of epithelial cells was significantly higher in the HGF group compared to the NG group, whereas mesenchymal cells from both groups were negative for the proliferative markers. Conclusion: Our data demonstrated that, in the studied family, HGF is transmitted by an autosomal dominant pattern with incomplete disease penetrance, and although the gingival enlargement resulted from an excessive accumulation of collagen fibers, HGF is characterized by an increase in the proliferation rate of epithelial cells.