Therefore, we suggest routine performance of molecular analysis of cartilaginous tumors in patients with OD, and, if IDH1 132H mutation is detected, performance of close surveillance through periodical ambulatorial and radiological control with contrast-enhanced MRI of the brain, to detect the eventual CNS tumor when asymptomatic and of small size, to plan the best management. This evidence concerns the gene IDH1 and chondrogenic neoplasm.