Calcifying tissue of florid cemento‐osseous dysplasia easily involving chronic diffuse sclerosing osteomyelitis

Florid cemento-osseous dysplasia (FCOD) is a benign, non-neoplastic lesion characterized by multiple sclerosing masses only within jawbones. It is frequently confused with chronic diffuse sclerosing osteomyelitis (CDSO) in the literature. Two cases of FCOD are examined to determine the characteristics of their calcifying tissues. The first case was non-infected, while the second case was severely infected, displaying the typical features of CDSO in clinico-radiologic findings. The infected FCOD case showed large bacterial colonies in the main lesion with rare inflammatory reaction. The globular cementum-like materials of FCOD looked like woven bone and showed increased positive reaction to Alcian blue stain, of which peripheral margin was strongly positive for the antibody of ameloblastin, and weakly positive for the antibodies of bone morphogenetic protein-2 and -4. In the immunostains of matrix metalloprotein-3, -9, -10, and transforming growth factor-alpha, macrophage infiltration in the FCOD lesion were rarely observed. These data suggest that the cementum-like materials of FCOD contain various matrix proteins, and that the cementum-like materials are relevant to the overgrowth of the bacterial colonies by the inhibition of regional inflammatory reactions.