Giant Cell Tumor

• Probably arise from zone of osteoclastic activity in skeletally immature patients
• Incidence
  • ~ 4% of all primary bone tumors
  • ~ 20% of benign skeletal tumors
• Histology
  • Multinucleated osteoclastic giant cells intermixed throughout a spindle cell stroma
• Age
  • > 98% after epiphyseal plate fusion
    • Most between 20 and 40 years
• M:F = 1:1
  
  
• Clinical
  
  
  • Tenderness
  • Pain at affected site
  • Weakness
  • Sensory deficits (if in spine)
    
    
• Location:
  
  
  • 85% in long bones
    • Lower extremity (50-60% about knee)
      • Distal femur > proximal tibia
    • Upper extremity (away from elbow):
      • Distal radius > proximal humerus
  • 15% in flat bones
    • Pelvis
    • Sacrum near SI joints
    • Skull
      
      
• Site in bone
  
  
  • Eccentric
  • Metaphyseal
    • Adjacent to epiphyseal line
      • Subarticular if epiphyseal plate is fused

Four views of the wrist show a lytic, eccentric and slightly expansile, geographic
lesion in the distal radius and extends to the end of the bone

• Appearance
  
  
  • Expansile
  • Solitary lytic bone lesion
  • May be quite large at diagnosis
  • No  reactive sclerosis
  • No periosteal reaction in absence of fracture
  • May break through cortex with cortical thinning
  • Soft-tissue invasion (25%)
  • Pathologic fracture (5%)
  • Destruction of vertebral body with secondary invasion of posterior elements (DDx: ABC, osteoblastoma)
    • Frequently demonstrate vertebral collapse
    • Can involve adjacent vertebrae and disk (like discitis) and can cross sacroiliac joint
  • May cross joint space in long bones (exceedingly rare)
• Nuclear medicine findings
  • Diffusely increased uptake
  • May have "doughnut" sign of central photopenia
• Angiographic findings
  • Hypervascular lesion
• CT findings
  • Tumor has soft-tissue attenuation
    • May contain foci of low attenuation (hemorrhage/necrosis)
  • Well-defined margins
  • May have thin rim of sclerosis
• MR findings
  • Heterogeneous signal intensity with low to intermediate intensity on T1WI + T2WI (63-96%) due to collagen + hemosiderin content
  • Focal cystic areas
  • Low-signal-intensity pseudocapsule
    
    
• Complications and associations
  
  
  • 15% malignant within first 5 years
    • Much more often in males (M:F = 3:1)
  • Metastases to lung
  • May be associated with
    • Paget disease (in 50-60% located in skull + facial bones)
      
      
• Prognosis
  
  
  • Locally aggressive
  • 40-60% recurrence rate
    
    
• Treatment
  
  
  • Complete resection  + radiation therapy
    
    
• DDx:
  
  
  • Aneurysmal bone cyst
  • Brown tumor (lab values)
  • Cartilaginous tumor
    • Chondroblastoma (open epiphyses)
    • Enchondroma (not epiphyseal)
    • Chondromyxoid fibroma (rare)
    • Chondrosarcoma
  • Fibrous dysplasia