A Rare Case Of Dedifferentiated Chondrosarcoma: Discrepancy Between Imaging And Histopathology Examination

Chondrosarcoma is a malignant tumor that produces cartilage matrix occurring in the third to sixth decades and has a male to female ratio of 2:1. Dedifferentiated chondrosarcoma is the most malignant form of chondrosarcoma and rare in its occurrence, accounting for approximately 10% of all chondrosarcomas, and is resistant to chemotherapy and radiotherapy. We reported a case of a 50-year-old woman having persistent and severe pain over her left distal thigh accompanied by progressive swelling in the thigh since 5 months ago. Laboratory tests were within normal limits. Imaging examination revealed a large soft tissue mass with moth-eaten pattern lytic lesion, wide zone transition, cortex destruction, with hair-on-end periosteal reaction, but there was no sign of abrupt transition between lytic lesion and cartilaginous tumor, which is indicative of dedifferentiated chondrosarcomas. Confirmation with histopathology study is consistent with the diagnosis of dedifferentiated chondrosarcoma. The correlation between clinical, radiographic findings, and histopathology study is essential for accurate diagnosis and optimal clinical management of dedifferentiated chondrosarcomas.