Our study confirmed that mitotic figures and nuclear pleomorphism are hallmarks of high-grade secondary peripheral chondrosarcoma. However, despite the substantial agreement, we demonstrated that histology alone cannot distinguish osteochondroma from low-grade secondary peripheral chondrosarcoma in the setting of multiple osteochondromas, since nodularity, the presence of binucleated cells, irregular calcification, cystic/mucoid changes and necrosis were not helpful to indicate malignant transformation of an osteochondroma. On the other hand, among the concordant cases, the cailage cap in osteochondroma was significantly less thick than in low- and high-grade secondary peripheral chondrosarcoma. Therefore, our study showed that a multidisciplinary approach integrating clinical and radio graphical features and the size of the cailaginous cap in combination with a histological assessment are crucial to the diagnosis of cailaginous tumors. REF <a href="