Chondrosarcoma is a malignant bone tumor arising from cartilaginous tissue, most frequently occuring at the ends of the femur and tibia, the proximal end of the humerus and the pelvis; and presenting with a palpable mass and progressive pain. Chondrosarcoma is usually slow growing at low histological grades and can be well managed by intralesional curettage or en-block wide resection.
Osteoporosis is a systemic skeletal disease characterized by low bone density and microarchitectural deterioration of bone tissue with a consequent increase in bone fragility. According to the WHO criteria, osteoporosis is defined as a BMD that lies 2.5 standard deviations or more below the average value for young healthy adults (a T-score below -2.5 SD).
Regional osteoporosis, although rarely described in synovial chondromatosis, was considered as the diagnosis in this patient, but a low grade primitive chondrosarcoma must be sought in such cases.
