Osteosarcoma associated with Paget's disease: a description of a rare case.

Osteosarcoma associated with Paget's disease is very malignant and has an extremely severe prognosis. This is also related to the usually advanced age of the patient and to the consequent impossibility of carrying out suitable chemotherapy. The case presented here is exceptional because of the young age of the patient, which allowed us to use a neoadjuvant chemotherapy protocol.