Gsalpha gene mutations in monostotic fibrous dysplasia of bone and fibrous dysplasia-like low-grade central osteosarcoma.

A series of nine cases with monostotic fibrous dysplasia (FD) and five cases of fibrous dysplasia-like low-grade central osteosarcoma (fd-like lgcOSA) were applied in a mutational analysis. Restriction digestion analysis, single-stranded conformational polymorphism (SSCP) analysis, and repeated sequencing demonstrated a R201H mutation in six cases and a R201C mutation in three cases of patients with monostotic FD. These results demonstrate that the presence of Gsalpha gene mutations is a constant finding in monostotic FD. To our knowledge, this is the first report in the literature investigating Gsalpha gene mutations in lgcOSA, which is one of the most important differential diagnoses of FD because of its low-grade malignant behavior. In four of five cases of fd-like lgcOSA, no mutation has been detected. In one case of this tumor, a R201C mutation could be demonstrated. Because our results demonstrate a low prevalence of Gsalpha gene mutations in this tumor in contrast to monostotic FD, mutational analysis may be an additional helpful parameter in individual cases for the differential diagnosis of FD and fd-like lgcOSA.