Osteosarcoma

Background

• Most common primary pediatric bone tumor
  • 3% of all childhood cancers
• Around two-thirds of those diagnosed with non-metastatic disease under the age of 40 will be long-term survivors or cured of the disease with appropriate treatment
• Survival is less than 20 percent with metastatic disease
  • One-fifth will have metastases at presentation
  • Most common metastatic site is lung followed by bone
• Bimodal as it peaks in early adolescence and over the age of 65

Pathophysiology

• Overproduction of osteoid and immature bone by malignant osteoblasts

Clinical Features

• Often an adolescent during a growth spurt
• Bone pain for several months that worsens with activity and is more painful at night
• Absence of constitutional symptoms (e.g., fevers, weight loss, night sweats, and decreased appetite are typically absent)
• Large soft tissue mass on exam that is tender to palpation
• Occurs at metaphysis of long bones
  • Most commonly at the distal femur followed by the proximal tibia
• Less frequently presents as pathological fracture
• Risk factors include prior cancer treatment, Paget disease of bone, benign bone disease, Hereditary Retinoblastoma or Li-Fraumeni syndrome

Differential Diagnosis

Malignant

• Multiple myeloma
• Chondrosarcoma
• Paget disease
• Ewing sarcoma
• Giant cell tumor
• Adamantinoma
• Chordoma
• Primary bone lymphoma
• Fibrosarcoma
• Myosarcoma
• Abscess

Benign

• Chrondroblastoma
• Enchondroma
• Langerhans cell histiocytosis of bone
• Osteoblastoma
• Osteochondroma
• Osteoid Osteoma

Evaluation

• X-ray
  • "Sunburst" pattern on X-ray
    • This pattern describes a lytic lesion with periosteal reaction and cortical disruption at or near the metaphysis
    • 

      (A) Sunburst appearance of Osteosarcoma.
      

      (B) Ultrasound of same patient showing cortical destruction and boney mass.
  • Codman triangle
    • New subperiosteal bone formed when the periosteum is raised away from the bone
• Elevated alkaline phosphatase
• Elevated LDH
  • High LDH associated with poor outcome
• Elevated ESR
• MRI and biopsy for definitive diagnosis

Management

• Pain control
• Limb sparing surgery or amputation, if needed
  • Depends on location and extent of the primary tumor
• Neoadjuvant chemotherapy
  • Response is a major prognostic factor
• MAP therapy (methotrexate, doxorubicin, cisplatin) often regimen of choice for non-metastatic disease
  • No standard approach if metastatic
• Typically, radiation resistant
  • If at base of skull or sacrum can consider intensity-modulated radiation therapy

Disposition

• Home if patient can get expedited follow up
• Admission and work-up if suspected delay in outpatient care