Frequent immunoexpression of TGF-β1, FGF-2 and BMP-2 in fibroblast-like cells in osteofibrous dysplasia

Osteofibrous dysplasia (OFD) and fibrous dysplasia (FD) are both benign bone lesions which comprise the proliferation of fibroblast-like cells with bone formation, and these fibroblast-like cells have the phenotype of osteoprogenitor cells. The roentgenograph of OFD shows a heterogeneous osteolytic lesion with surrounding osteosclerosis, whereas FD is typically characterized by a rather homogeneous osteolytic lesion, or 'ground-glass appearance', with a smaller amount of surrounding osteosclerosis. Growth factors of transforming growth factor-β1 (TGF-β1), fibroblast growth factor-2 (FGF-2) and bone morphogenetic protein-2 (BMP-2) modulate bone differentiation. Expression of these growth factors was examined in the fibroblast-like cells of 16 cases of OFD and 16 cases of FD, immunohistochemically. TGF-β1 in fibroblast-like cells was frequently expressed both in the OFD (16/16) and the FD (15/16) cases. The frequency of FGF-2 (16/16) expression and BMP-2 (13/16) expression in the fibroblast-like cells of OFD was higher than that of those [FGF-2 (8/16) and BMP-2 (6/16)] in the fibroblast-like cells of FD, with a statistical significance. These results seem to suggest that fibroblast-like cells of OFD have greater bone-forming ability than those of FD, and may explain the roentgenographic difference between OFD and FD and a difference in the nature of fibroblast-like cells between these two types of lesions.