Clear cell chondrosarcoma of the pelvis in a skeletally immature patient.

We report on a case of clear cell chondrosarcoma (CCCS) of the left iliac bone in a 12-year-old skeletally immature boy. Radiographic examination revealed an aggressive osteolytic lesion with areas of mineralization. Fluid-fluid levels were seen on T2-weighted MR images. Laboratory data showed slight elevation of serum alkaline phosphatase. The biopsy specimen showed histological features of CCCS with some resemblance to osteosarcoma, such as prominent irregular osteoid formation among clear tumor cells. Surgical treatment was accomplished without pre- or post-operative chemotherapy. Because of the patient's age, elevated serum alkaline phosphatase, and histopathology with prominent osteoid production, this case could be confused with osteosarcoma. Although CCCS is an extremely rare bone tumor in children, it is important to be aware that it may arise in a skeletally immature patient. CCCS, unlike osteosarcoma, is not treated with neo-adjuvant chemotherapy.