Osteosarcoma

Background

Osteosarcoma occurrence sites

• 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% 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

Bone tumors and their mimics

Malignant

• Multiple myeloma
• Chondrosarcoma
• Paget disease
• Osteosarcoma
• Adamantinoma
• Chordoma
• Primary bone lymphoma
• Fibrosarcoma
• Myosarcoma

Benign

• Giant cell tumor
• Chrondroblastoma
• Enchondroma
• Langerhans cell histiocytosis of bone
• Osteoblastoma
• Osteochondroma
• Osteoid osteoma

Other

• Septic joint
• Fracture
• Abscess

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 in (A) 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