The significance of electron microscopic examination of gingiva in cases of Hunter syndrome and hereditary gingival fibromatosis.

INTRODUCTION: Electron microscopy has been for decades a basic morphological method still used in diagnostic protocols of some pathological conditions affecting the ultrastructure of cells and extracellular matrix. The aim of this study was an ultrastructural description of gingiva of patients with Hunter syndrome and hereditary gingival fibromatosis.

PATIENTS AND METHODS: Gingival biopsies were obtained during surgical periodontal treatment from a 9-year-old boy with Hunter disease (with enzyme replacement therapy with recombinant human idursulphase) and a 15-year-old girl with hereditary gingival fibromatosis. Gingival samples obtained from the upper anterior region were processed and examined with transmission electron microscope.

RESULTS: In the case of Hunter syndrome due to the genetic lack of one lysosomal enzyme, an intercellular accumulation of glycosaminoglycans occurs. Within the gingiva of a patient with Hunter syndrome we observed membrane-bound storage vesicles in the cytoplasm of fibroblasts, endothelial cells of capillaries, surface epithelial cells, mast cells, and macrophages. Despite a long-term enzyme replacement therapy which improves clinical manifestations of Hunter syndrome, on the cellular level we still found marked accumulations of glycosaminoglycans in the cytoplasm of different cells as well as in the extracellular matrix. Hereditary gingival fibromatosis is a benign, slowly progressive and non-inflammatory gingival enlargement with a predominance of randomly oriented collagen fibrils in the gingival lamina propria. Some of these fibrils exhibited loops. Another unusual ultrastructural finding is the presence of empty perinuclear space in the cytoplasm of epithelial cells. The origin and significance of these non-membrane bound spaces are unknown.

CONCLUSION: In both genetically determined diseases, the electron microscopic examination may be useful, and physicians get relevant information about the progress of illness.