Snapshot A 68-year-old man presents to his primary care physician for left leg pain. His pain has been progressively worsening over the course of a month and is present at night. Physical examination demonstrates impaired left lower extremity weakness limited by pain. A radiograph of the left hip and femur demonstrates lytic lesions and intralesional calcifications. Introduction Overview malignant tumor that produces chondroid matrix by chondrocytes Epidemiology Incidence 3rd most common primary malignancy of bone ETIOLOGY Pathophysiology primary chondrosarcoma arises de novo secondary chondrosarcoma arises from preexisting cartilage lesions osteochondroma endochondroma has a predilection for the axial skeleton pelvis and ribs femur humerus Presentation Symptoms pain at the site of involvement can be present at night Physical exam tenderness to palpation at the site of involvement neurologic dysfunction if there are pelvic lesions close to the neurovascular bundle Imaging Radiography indication initial imaging study findings lytic lesions intralesional calcifications e.g., "popcorn calcifications" CT scan indication to detect subtle lesions or lesions that are found in anatomically complex areas MRI indication to evaluate the extent of the disease and soft tissue involvement Studies Invasive studies fine needle aspiration or core biopsy indication confirms the diagnosis findings malignant chondrocytes in gelatious cartilaginous matrix it is often difficult to determine malignancy based on histology alone Differential Osteosarcoma differentiating factors histology demonstrates pleomorphic osteoid-producing cells Ewing sarcoma differentiating factors anaplastic small, round, and blue cells with scant cytoplasm typically affects the diaphysis Treatment Surgical intralesional curettage indications low-grade chondrosarcoma wide en bloc local excision indication intermediate- and high-grade tumors Complications Fractures Metastasis (however, has low metastatic potential) Prognosis Prognostic variable favorable location where complete wide resection can be performed the lower the tumor grade