Significant association between FGFR1 mutation frequency and age in central giant cell granuloma.

Central giant cell granulomas (CGCG) are rare intraosseous osteolytic lesions of uncertain aetiology. Despite the benign nature of this neoplasia, the lesions can rapidly grow and become large, painful, invasive, and destructive. The identification of molecular drivers could help in the selection of targeted therapies for specific cases. TRPV4, KRAS and FGFR1 mutations have been associated with these lesions but no correlation between the mutations and patient features was observed so far. In this study, we analysed 17 CGCG cases of an Italian cohort and identified an interesting and significant (p=0.0021) correlation between FGFR1 mutations and age. In detail, FGFR1 mutations were observed frequently and exclusively in CGCG from young (<18 years old) patients (4/5 lesions, 80%). Furthermore, the combination between ours and previously published data confirmed a significant difference in the frequency of FGFR1 mutations in CGCG from patients younger than 18 years at the time of diagnosis (9/23 lesions, 39%) when compared to older patients (1/31 lesions, 0.03%; p=0.0011), thus corroborating our observation in a cohort of 54 patients. FGFR1 variants in young CGCG patients could favour fast lesion growth, implying that they seek medical attention earlier. Our observation might help prioritise candidates for FGFR1 testing, thus opening treatment options with FGFR inhibitors.