Features of central giant cell granuloma of the jaws xenografted in nude mice.

In order that the growth pattern and histologic and ultrastructural differentiation of the central giant cell granuloma of the jaws be studied, tissue from three lesions was transplanted into nude mice. Xenografts were harvested at 3 weeks, 5 weeks, 8 weeks, and 13 weeks and examined histologically and ultrastructurally. Implants could be identified as firm subcutaneous nodules, but after 3 weeks began regressing. At 13 weeks, almost total regression had occurred. Histologically, grafts were well vascularized and there was no evidence of necrosis. Typical multinucleated giant cells disappeared at an early stage. The ultrastructural features of the grafts showed giant cells lying in close association with uninuclear cells, features suggestive of a fusion process. Many cells containing microfilaments at their periphery were identified in the original lesional tissue as well as in the xenografts. These cells strongly resembled myofibroblasts. Collagen bundles were seen within the cytoplasm of stromal cells. The observations suggest that the multinucleated giant cells represent a stimulus-dependent, differentiated end-stage cell population.