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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
Campanacci Radiological Grading System for Giant Cell Tumours of Bone
Grade Description
1 Intramedullary lesion confined to bone
2 Thinned, expanded cortex
3 Cortical breakout

Enneking

  • Radiological & histological classification
  • Corresponding to clinical presentations
Enneking Classification of Giant Cell Tumours of Bone
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
Malignant Very rare
  • Sarcomatous lesion contiguous with benign GCT

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
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