OSTEOSARCOMA
 
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OSTEOSARCOMA

 

DEFINITION:

A malignant osteogenic tumor of bone characterized usually by limb pain and swelling.

EPIDEMIOLOGY:

  • incidence: 3.36/million
    • 5th most common extracranial solid tumor in children
    • represent 60% of all bone tumors in children and adolescents
  • age of onset:
    • peaks between 15-25 years of age
  • risk factors:
    • whites > blacks
    • M = F (before adolescents)
    • M > F (after " - 1.6:1)
    • prior therapeutic radiation to bone (i.e. Ewings Sarcoma)
    • exposure to radioactive substances
    • retinoblastoma
    • long-standing Paget disease

PATHOGENESIS:

1. Tumor Origin

1. Long bones

  • distal femur > proximal tibia > proximal humerus
  • metaphysis (90%), diaphysis (10%)

2. Histologic Types

1. Medullary

  • chondroblastic
  • fibroblastic
  • osteoblastic
  • telangiectasia (based on preponderance of matrix within tumor)

2. Cortical (surface)

  • parosteal (juxtacortical)
  • periosteal

3. Background

  • multifocal sclerosing osteosarcoma is a rare variant
  • silent pulmonary micrometastases are present in 80-90% of patients at the time of diagnosis and become radiographically apparent after 6-9 months and are usually the cause of death
  • about 10-20% of patients have overt lung mets at diagnosis

CLINICAL FEATURES:

1. Primary Tumor

  • knee pain and/or hip pain
  • swelling, mass, increased temperature over tumor site
  • limp if in leg (occur around knee 80% of the time)
  • decreased range of motion of joints located proximal and distal to the tumor - +/- lymph node involvement

2. Metastases

  • systemic signs (weight loss, fever) suggest mets have occurred
  • lungs - pleural effusion, pneumothorax
  • lymph nodes, bone marrow, pericardium, kidney, brain

INVESTIGATIONS:

1. Imaging Studies

1. Skeletal X-Ray

  • variable from blastic to lytic
  • "sunburst"
  • "Codman triangle" - elevation of the periosteum adjacent to the tumor

2. Bone Scan

  • increased uptake of technecium

3. Others

  • Bony CT/MRI
  • Chest X-Ray/CT - mets

2. Pathology

1. Tumor Site

  • open vs closed biopsy
  • examine for different histiological types of tumor cells & anaplastic spindle-shaped cells

2. Bone Marrow

  • aspirate for mets

MANAGEMENT:

1. Surgery

  • excision - amputation vs segmental resection

2. Chemotherapy

1. Pre-operatively

  • CDP for 3 months to induce necrosis of tumor and destroy pulmonary micrometasteses

2. Post-operatively

  • MTX-CF, ADR, CTX, IFX, phenylalanine mustard

DIFFERENTIAL DIAGNOSIS:

1. Malignant Neoplastic Tumors

  • Chondrosarcoma
  • Ewing Sarcoma
  • Fibrosarcoma
  • Juxtacortical Osteosarcoma
  • Rhabdomyosarcoma or Soft Tissue Sarcoma

2. Benign Neoplastic Tumors

  • Aneurysmal Bone Cyst
  • Chondroblastoma
  • Chondromyxoid Fibroma
  • Giant Cell Tumor
  • Langerhan Cell Histiocytosis
  • Osteoblastoma
  • Osteochondroma
  • Unicameral Bone Cyst

3. Nonneoplastic Conditions

  • Hematoma
  • Osteomyelitis
  • Stress Fracture

 

 

Pediatric Database - OSTEOSARCOMA

 

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