Myofibroblasts in central giant cell granuloma of the jaws: an ultrastructural study.

The ultrastructure of stromal mononuclear cells and giant cells were studied in two cases of central giant cell granuloma of the jaws. The majority of stromal cells superficially resembled fibroblasts, but also contained intracytoplasmic myofilaments with electron dense bodies similar to smooth muscle cells. These cells were referred to as myofibroblasts. The other type of mononuclear cells resembled macrophages. Many of the myofibroblast type cells appeared close to giant cells and signs of early fusion between them could be demonstrated. It is suggested from these results that the giant cells in central giant cell granuloma form and increase in size through fusion of these cells.