Primary Central Chondrosarcoma The primary or central conventional chondosarcoma is a lowgrade but malignant cartilagenous tumor found typically in adultsbetween the ages of 30 and 60 years. The tumor arises from themedullary canal of a large bone such as the pelvis, femur, tibia orproximal humerus. Because the tumor is slow growing, there islittle symptomatology and the tumor frequently becomes quitesizable before a physician is consulted. Primary chondrosarcomais extremely rare in small bones of the hand or foot. The meta-physeal portion of a long bone is the most common locationalthough diaphyseal locations are not unusual. 85% of centralchondrosarcomas are low grade lesions which on radiographicexamination demonstrate matrix calcification similar to that seenin benign enhondromas, whereas the high grade chondrosarcomas,which are rare, are frequently noncalcified and take on thepermeative appearance similar to other high grade sarcomas such
as fibrosarcoma and Ewing’s sarcoma. Histologically, the lowgrade central chondrosarcoma has a fairly well differentiatedchondroid matrix like that of an enchondroma but shows evidenceof permeative invasion into the adjacent cortical and cancellousstructures. There is rarely any mitotic activity in the low gradelesions. They have larger nuclear patterns with a higher degreeof atypicism compared to benign enchondromas. These low grade tumors have a good prognosis in terms of alow metastatic incidence to the lung but they must be treatedaggressively with a wide resection in order to prevent localrecurrence. One can not rely on adjuvant therapy such as radiationor systemic chemotherapy because these low grade lesions arenotoriously resistant to adjuvant therapy.
CLASSIC Case #125 50 year female with chondrosarcoma prox humerus
Secondary Peripheral Chondrosarcoma The vast majority of secondary peripheral chondrosarcomas arisefrom a prexisting osteochondroma and do not occur before puberty.These lesions tend to be slow growing with minimal to mildsymptoms. The most common site is the pelvis, followed by theproximal femur, proximal humerus, and ribs. Plain radiographs showa large calcifying mass on the surface of bone that measure over5 cm in girth. When one sees an osteochondroma with a cartilagenouscap over 3 cm in thichness, there is a strong likelihood for asecondary chondrosarcoma. The overall prognosis for the secondaryperipheral chondrosarcoma is much better than that for the primarycentral chondrosarcoma and usually requires only a simple wideresection with little chance for local recurrence.
CLASSIC Case #126 exostosis tumor56 year male with 2ndary peripheral chondrosarcoma ilium
Dedifferentiated Chondrosarcoma Of all the chondrosarcoma variants, by far the most malignant andpotentially fatal is the dedifferentiated chondrosarcoma thataccounts for approximately 5-10% of all chondrosarcomas. Itmost likely arises as a result of a second mutation within a pre-existing low to intermediate grade chondrosarcoma, resulting inthe formation of a malignant fibrous histiocytoma or osteo-sarcoma immediately adjacent to the lower grade chondrosarcoma.Histologically, the low and high grade portions of this tumor aregeographically separated by sharp margins. These tumors usuallyoccur in patients between the ages of 50 and 70 years in thesame areas where primary central chondrosarcomas are found:the pelvis, femur and proximal humerus. The characteristicradiographic appearance is that of a flocculated calcific lyticlesion arising from the central area of bone with an adjacent areawith more extensive infiltration into the surrounding cortical bone.
There is no evidence of calcification in the high grade portion of thelesion and it typically breaks through the cortex and into thesubperiosteal space. The prognosis for this variant of chondrosarcomqa is extremelypoor, most patients dying from metastatic disease within one or twoyears after the diagnosis is established. Adjavent chemotherapy orradiation therapy is not very effective, mainly because of the olderage group in which the tumor occurs. The primary treatmentmodality is wide surgical resection.
CLASSICCase #12744 year malededifferentiatedchondrosarcomaproximal femur
Clear Cell Chondrosarcoma The clear cell chondrosarcoma is one of the rarest variants of thechondrosarcoma. It is found more commonly in males than femalesbetween the ages of 20 and 50 years. The most common locationfor this tumor is in the femoral head. Radiographically the clear cellchondrosarcoma has the appearance of a lytic lesion in the epiphysis,similar to the chondroblastoma in a younger age group for which itis frequently misdiagnosed. It has a geographic pattern with centralstippled calcification similar to that of a chondroblastoma. Histo-locally it also has the appearance of a chondroblastoma with thepresence of benign macrophages and polyhedral stem cells with aclear cell chicken wire appearance. But in some areas one will seeevidence of a low grade chondrosarcoma in which giant cells are notseen, clearly separating it from the chondroblastoma. The treatment for this condition consists of a wide resection whichin the femoral head would be a transcervical resection and replace-
ment with a bipolar prosthesis. If the lesion is treated by simplecurettement, the recurrence rate is quite high compared to thechondroblastoma. The chance for pulmonary metastasis is veryunlikely and local recurrence is rare following a wide resection.
CLASSIC Case #12825 year male with clear cell chondrosarcoma femoral head
Mesenchymal Chondrosarcoma The mesenchymal chondrosarcoma is another rare variant of thechondrosarcoma. It consists of low grade chondrosarcoma com-ponents with an infiltration of primitive mesenchymal cells givingit the histological appearance of a Ewing’s sarcoma or a hemangio-pericytoma. It can be seen in soft tissue as well as bone in youngadults, more often in females. The most common location is in thejaw, followed next by the spine or ribs, with a very few cases seenin long bones. Because of the high grade component of this lesion,it is treated as a high grade sarcoma with adjavent chemotherapyand radiation therapy along with a wide resection if possible.Despite this aggressive program of treatment, the prognosis is verypoor because of a high incidence of pulmonary metastases andlocal recurrence.
CLASSICCase #12934 year femalemesenchymalchondrosarcoma tumorLD spine & paraplegiaSagittal MRI