Osteosarcoma
Osteosarcoma is a malignant osteoid-producing bone tumor with a bimodal age distribution, most often arising in the metaphysis around the knee in adolescents and young adults. Diagnosis rests on radiograph findings of Codman triangle or sunburst periosteal reaction confirmed by biopsy, and treatment sequences neoadjuvant chemotherapy, limb-sparing wide resection, and adjuvant chemotherapy.
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What this article covers
- Overview
Definition: osteosarcoma is a malignant bone tumor composed of pleomorphic osteoblasts that directly produce osteoid, arising most often in the metaphysis of a long bone.
- Epidemiology
Most common primary bone sarcoma: osteosarcoma accounts for roughly 20% of primary bone cancers and is the most common primary malignant bone tumor in children and adolescents; among all primary bone…
- Risk factors
Li-Fraumeni syndrome: germline TP53 mutation; loss of p53 function (normally activating p21 to block G1 to S) predisposes to early-onset osteosarcoma among other cancers.
- Pathophysiology
Malignant transformation of osteoblasts: tumor cells are pleomorphic, malignant osteoblasts that directly produce osteoid and immature woven bone, distinguishing osteosarcoma from cartilage- or marrow-derived bone tumors.
- Clinical features
Progressive bone pain: dull, deep pain that is initially intermittent and activity-related but becomes constant and characteristically worse at night, often mistaken for growing pains in a child or adolescent, which can delay diagnosis.
- Differential diagnosis
Ewing sarcoma: also a painful bone mass in a child or young teen, but arises in the diaphysis or pelvic flat bones with an onion-skin periosteal reaction and small round blue cells carrying the…
- Diagnosis
Confirmed by biopsy showing malignant osteoid-producing cells: there is no formal clinical scoring system; the diagnosis is established when biopsy of the lesion, performed by the treating orthopedic…
- Management
Refer to an orthopedic oncologist and complete staging (MRI of the bone, chest CT, bone scan/PET) before any biopsy or treatment decision, because biopsy technique and treatment sequencing both depend on accurate local and distant staging.
- Complications
Pulmonary metastasis: the dominant pattern of distant spread and the leading cause of death; may be present at diagnosis or develop later.
- Prognosis
Survival depends on metastasis at diagnosis and histologic response to chemotherapy: localized disease treated with combined chemotherapy and surgery achieves the best outcomes, while metastatic…
- Prevention
No population screening exists for osteosarcoma; prevention is limited to surveillance of predisposing conditions and avoidance of modifiable risk exposure.
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