[Chondrosarcoma arising in solitary osteochondroma: a case study].

Chondrosarcoma is a rare malignant bone tumor. It can arise de novo or secondary to a malignant transformation of a benign underlying cartilage tumor. Secondary chondrosarcoma arising from solitary benign osteochondroma is extremely rare and data show that the reported incidence of osteochondroma of the pelvis is very low. We here report the case of a 20-year old patient with chondrosarcoma secondary to malignant transformation of an osteochondroma of the right wing of ilium, adjacent to the sacroiliac joint.