Immunohistochemical and ultrastructural evidence of a modified microvasculature in the giant cell granuloma of the jaws.

A panel of five immunohistochemical markers, MB1, leukocyte common antigen, S-100 protein, smooth muscle specific actin, and factor VIII related antigen, were used to study 20 giant cell lesions. These included eight central giant cell granulomas, nine peripheral giant cell granulomas, and three giant cell tumors of bone. The multinucleated giant cells stained positively with MB1, the mononuclear round cells were positive to leukocyte common antigen and the spindle cells were unreactive to all the markers chosen in all the lesions. The most interesting finding was the staining pattern of the blood vessels to factor VIII related antigen in the giant cell granuloma. The blood vessels on the periphery of the lesions were strongly positive for this antibody. However, reaction product was not evident deeper in the lesion within the aggregations of giant cells. Two other endothelial cell markers, Ulex europaeus 1 lectin and QBend 10 were used to study 10 giant cell lesions and a similar pattern of staining was observed. Transmission electron microscopy was subsequently used to study the ultrastructure of the microvasculature of three peripheral giant cell granulomas, and the findings indicated that the reasons for the differential staining may lie in the differences in the structure of the microcirculation.