Rare Dedifferentiated Periosteal Chondrosarcoma with 11-Year Metastatic Relapse: A Case Report.

A 50-year-old man presented for evaluation of a periscapular mass. Biopsy suggested a low-grade chondrosarcoma; however, the resected specimen revealed a grade 2 chondrosarcoma with a low-grade dedifferentiated mesenchymal component. The mass multiply recurred as chondrosarcoma without a dedifferentiated component before the patient developed lung metastases of chondrosarcoma without a dedifferentiated component 11 years after the initial diagnosis and died of disease. This is one of the first reported cases of a dedifferentiated chondrosarcoma with low-grade dedifferentiated component. While overall prognosis may be better than in typical dedifferentiated chondrosarcoma, this tumor demonstrated numerous local recurrences as well as metastasis.