Overview
Osteosarcoma is the most common nonhematologic primary malignancy of bone and chondrosarcoma is the second most common. Both require a staged work-up before biopsy, and outcome depends on grade, size, location, metastases and achieving adequate surgical margins. (Campbell)
Osteosarcoma
Presentation and imaging
Nearly all high-grade patients report progressive pain; night pain is present in only about 25%. Pain may initially improve with rest, giving false reassurance. In one study the average delay to diagnosis was about 15 weeks (6 weeks patient delay, 9 weeks physician delay), mainly from failure to obtain radiographs, or to repeat them when symptoms persisted or worsened.
Typical sites are the distal femur, proximal tibia and proximal humerus, at the sites of fastest growth. The classic radiograph shows a permeative, ill-defined metaphyseal lesion with mixed bone formation and destruction, Codman triangle or sunburst periosteal reaction, and sometimes a soft-tissue mass.
MRI best defines intraosseous and soft-tissue extent. Obtain bone scan (or FDG PET-CT) and chest radiograph and CT before biopsy, since the lung is the most common metastatic site.
Subtypes
Conventional: high-grade intramedullary tumor; diagnosis requires osteoid production by tumor cells.
Parosteal: low-grade surface tumor, a lobulated ossified mass typically on the posterior distal femur, with late medullary invasion. CT helps separate it from myositis ossificans (more mature at the periphery) and osteochondroma (marrow continuity with host bone).
Periosteal: intermediate grade, surface, usually femoral or tibial diaphysis.
High-grade surface: aggressive, with frequent medullary involvement.
Low-grade intramedullary: indolent, may mimic fibrous dysplasia or osteoblastoma.
Telangiectatic: purely lytic and blood-filled, may mimic an aneurysmal bone cyst; the septal cells are frankly malignant.
Small cell: may resemble Ewing sarcoma or lymphoma.
Secondary: about half of osteosarcomas after age 50. Paget disease (about 1%, up to 5 to 10% in advanced polyostotic disease) and prior radiation (about 1% after more than 2500 cGy, typically 10 to 15 years later).
Treatment
High-grade: neoadjuvant chemotherapy, wide or radical surgery (resection or amputation), then adjuvant chemotherapy; resect pulmonary metastases when possible. Historically, amputation alone left about 80% dead of metastases, implying micrometastases at presentation.
Histologic response to chemotherapy predicts survival; more than 90% necrosis is a very good sign.
Low-grade lesions are treated by wide resection or amputation without chemotherapy.
Pathologic fracture worsens survival and metastasis risk but not necessarily local recurrence, so limb salvage may remain an option in selected patients.
Recurrence and prognosis
About 50% of high-grade patients relapse; about 10% have local recurrence after wide surgery, usually treated by radical amputation plus chemotherapy.
Poor factors: rapid relapse, more than eight nodules, nodules over 3 cm, unresectable nodules. A few small, late, resectable nodules may carry up to a 60% chance of cure.
Long-term survival is 60% to 75% for nonmetastatic high-grade disease and about 90% for low-grade. About 15% have lung metastases at diagnosis (under 20% survival, over 50% with one or few resectable nodules); bone metastases or skip metastases carry a very poor prognosis. Larger and more proximal tumors do worse; Paget osteosarcoma has under 15% survival.
(Campbell)
Chondrosarcoma
Presentation and imaging
Peak age 40 to 60 years (primary) and 25 to 45 years (secondary), usually in the pelvis, proximal femur and proximal humerus. It is the most common primary bone malignancy of the hand, although rare there.
Increasing pain or a mass, often over years. Pain without fracture helps separate low-grade chondrosarcoma from enchondroma, whereas an asymptomatic incidental cartilage lesion is very rarely chondrosarcoma.
Medullary lesion with punctate, popcorn or comma-shaped calcification, plus bone destruction, cortical erosion, periosteal reaction or soft-tissue mass. CT shows endosteal erosion. Location matters: the same cortical destruction that is benign in the hand indicates chondrosarcoma in the pelvis or proximal femur. In an osteochondroma, a cap over 2 cm in a skeletally mature patient raises concern for secondary chondrosarcoma.
Secondary disease arises in multiple enchondromatosis (about 25% by age 40 in Ollier disease), Maffucci syndrome, and osteochondromas (about 5% multiple, about 1% solitary, likely overestimated). Prophylactic treatment of asymptomatic solitary enchondromas is not warranted.
Histology
Malignant cells with abundant cartilage matrix (malignant osteoid means chondroblastic osteosarcoma instead). Favoring malignancy: hypercellularity, plump nuclei, frequent binucleate cells, permeative growth and entrapped trabeculae. Sample as much tissue as possible and correlate with imaging. Subtypes (under 20% together): dedifferentiated (high-grade spindle cell sarcoma beside low-grade chondrosarcoma), clear cell (low grade, epiphyseal, can mimic chondroblastoma or giant cell tumor) and mesenchymal (high grade, small round blue cells).
Treatment
Extended curettage with adjuvants is adequate only for low-grade lesions confined to the medullary canal; those with soft-tissue extension are treated like high-grade lesions.
High-grade: wide or radical resection or amputation. Cartilage cells survive implantation easily, so contamination causes high local recurrence; in an expendable location primary wide resection without biopsy may be considered.
Chemotherapy has no role in conventional chondrosarcoma but is used for dedifferentiated and mesenchymal types. Radiation is only palliative for inaccessible lesions.
After wide resection, local recurrence is under 10%; treat with repeat wide resection or amputation, and resect lung metastases if possible.
Prognosis
Low-grade lesions have over 90% 10-year survival, high-grade conventional about 20% to 40%, and dedifferentiated 10% to 25% at 5 years. Late recurrence and metastasis occur, often at higher grade, so long-term imaging of the surgical site and chest is imperative. (Campbell)
References
Toy PC, Heck RK Jr. Malignant tumors of bone. In: Azar FM, Sawyer JR, Throckmorton TW, eds. Campbell's Operative Orthopaedics. 15th ed. Philadelphia: Elsevier; 2026. Chapter 29.