Giant Cell Tumour of Bone

  • AKA Osteoclastoma

Definition

  • Locally aggressive benign neoplasm of bone with tendency for local recurrence
  • Characterized by varying numbers of multinucleated giant cells in a stroma of round, ovoid or spindle shaped cells that fuse to form the giant cells of the lesion

Epidemiology

  • 4-5% primary bone tumours in USA (20% in China)
  • 20% of all benign bone tumours
  • Peak incidence in the 3rd-4th decade
  • M<F – 1:1.5
  • Most common in epiphyseal ends of long bones (may migrate to metaphysis)
  • Extending to & sometimes through the subchondral bone
    • 50% about the knee
    • Other common sites are
      • Distal radius
      • Proximal humerus
      • Spine rare
        • Consider pre-existing Pagets
        • Vertebral bodies involved (cf. osteoblastoma & ABC in posterior elements)
  • Rarely multicentric (< 1%)
  • In rare cases where it occurs in the child with open physis (< 2%) the lesion is metaphyseal
  • GCT of the small bones of hand & foot have younger age group & higher multicentricity
  • 5% pulmonary metastases
  • Consider GCT benign if pulmonary metastasis histologically benign
    • Regular CXR in patients with GCT

Aetiology

  • ? Tumour of Pre-osteoclasts
  • Also PVNS & Giant Cell tumour of Tendon Sheath

Classification

Jaffe & Lichenstein

  • Histological classification system
    • Based on microscopy of background stromal cells
    • Not proven to be predictive
    • Histology shows no correlation to aggressiveness of lesion

Campanacci

  • Radiological grading system
    • Better for prognosticating aggressiveness then histology
GradeDescription
1Intramedullary lesion confined to bone
2Thinned, expanded cortex
3Cortical breakout
Campanacci Radiological Grading System for Giant Cell Tumours of Bone

Enneking

  • Radiological & histological classification
  • Corresponding to clinical presentations
Stage%Description
Stage I (latent)15%Confined totally by bone
Asymptomatic
Inactive on bone scan
Histologically benign
Stage II (active)70%Expanded cortex with no breakthrough
Symptomatic
If pathological fracture
Active on bone scan
Histologically benign
Stage III (aggressive)15%Rapidly growing mass
Cortical perforation with soft tissue mass
May metastasize
Symptomatic
Extensive activity on bone scan
Histologically benign
MalignantVery rareSarcomatous lesion contiguous with benign GCT
Enneking Classification of Giant Cell Tumours of Bone

Pathology

Gross

  • Homogenous lesion with tan colour & moderately firm consistency
  • Foci of haemorrhage and/ or necrosis seen in many tumours
  • Eccentrically located & extends up to articular margin
  • Overlying cortex expanded & tumour surrounded by subperiosteal new bone
  • The cystic/ haemorrhagic tumour may resemble ABC

Histology

  • Background of proliferating homogenous mononuclear stromal cells
    • Round to ovoid shape & relatively large nuclei with inconspicuous nucleoli
    • Within fibrous stroma
  • Multinucleated Giant cells dispersed throughout with similar appearance to osteoclasts
    • “Osteoclastoma”
    • 50-100 nuclei sometimes
  • Small stromal cells may be the tumour & the giant cells only reactive
  • Other areas may show lipid-filled histiocytes
  • Foci of reactive bone at periphery of tumour
  • Mitosis may be prominent & intravascular invasion do not indicate malignancy in GCT
    • Histologic appearance not related to biological behaviour
  • One of few benign tumors with areas of spontaneous necrosis

Clinical Features

  • 20-50 years old
  • Pain
  • Local swelling
  • Joint effusion
  • Muscle atrophy
  • Pathological fracture
  • Can be pulsatile

Investigations

X-ray

  • Well-defined lytic defect
    • Epiphysis & metaphysis
    • Eccentrically located
    • Extends to subchondral bone of articular surface
    • Can invade articular cartilage
  • Tends to be spectrum of disease
    • Benign-looking with well-defined sclerotic margin
    • More aggressive lesion with permeative appearance
  • No intralesional densities
  • May have cortical expansion with thin layer of subperiosteal new bone
  • ± Cortical breach & soft tissue extension
  • Differential for subarticular tumours
    • GCT
    • ABC
    • Chondromyxoid fibroma (in foot)

Bone scan

  • Increased uptake
  • May be diffuse (40%) or peripheral with little central activity (60%)
  • Non specific

Angiogram

  • Hypervascularity of lesion

CT Scan

  • Help evaluate cortical integrity & extraosseous extent & relationship to adjacent structures
  • Fluid levels may represent ABC component

MRI

  • Homogenous
  • Help to delineate the soft tissue margins

Laboratory Investigations

  • Serum Calcium & Serum Phosphate to rule out hyperparathyroidism
  • Brown’s tumour has similar radiological appearance
  • (GCT can occur in hyperparthyroidism also)

Differential Diagnosis

  • Chondroblastoma
  • ABC
  • Brown tumour
  • Osteomyelitis
  • Eosinophilic granuloma
  • Enchondroma
  • Non-ossifying fibroma
  • Unicameral bone cyst

Treatment

  • Biopsy usually performed

Principles

  • Excise the lesion
  • Sterilize the cavity
  • Reconstruct the defect

Traditional

  • Intralesional curettage & bone grafting
  • Local recurrence rates 40-60%
  • Difficult to do intralesional excision without leaving tumour cells behind
    • Because of proximity to articular cartilage

Modern Adjuvant Treatment

  • Adjuvant treatment used locally to extend clear margins & therefore ↓ recurrence
  • Extended Curettage with high speed burr
  • Adjunctive measures
    • Bone cement
      • PMMA packing
      • Recommended
      • Works by thermal necrosis
      • Bone graft for 1cm under subchondral plate (? Beneficial)
      • Waterpick+++
    • Phenol
      • Irrigation of cavity with phenol has high complication rate
      • OK if touch it with cotton bud
    • Cryotherapy
      • Liquid N2
  • Important principle is visualization of whole cavity through
    • Large cortical window
    • Thorough curettage
    • Coffee Cup Theory

Wide or Marginal Resection

  • Reserved for
    • Expendable bones
    • Recurrences
    • Bones destroyed beyond salvage
    • Grade III lesions
  • Requires extensive reconstruction often
    • Prosthesis
    • Allograft
    • Free fibular autograft
  • use of radiotherapy may be indicated in unresectable tumours (ie. spine) or recurrences
  • Use of radiotherapy related to sarcomatous change
    • Hence treatment plan
      • Stage I & II
        • Extended curette with high speed burr & adjuvant PMMA
      • Stage III & Recurrence
        • Wide resection & osteochondral allograft
      • Unresectable
        • Radiotherapy
        • Radiation suggested in sacrum & vertebral bodies where unresectable
        • Radiation may give rise to secondary malignant change
          • 19% sarcomatous change

Malignant Metastatic Disease

  • 2% will see lung secondaries
  • Often secondary to radiotherapy (10% after 5-8 years)
  • Features suggestive include
    • Crowding of stroma
    • Marked atypia
    • Increased mitotic activity
  • Progress slowly
  • Can see benign lung lesion associated with benign GCT
  • Resection is operation of choice

Prognosis

  • ~ 23% recurrence 3 years
  • Most recurrences occur within 2 years