Chondroblastoma

  • A benign tumor of cartilaginous origin with a predilection for the epiphysis in skeletally immature patients
    • “Codman’s tumour”
    • Epiphyseal chondromatous giant cell tumor

Defin>Definition

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  • Benign cartilage lesion
  • But aggressive/ frankly malignant behaviour reported
  • Arises in secondary ossification centre
  • Develops until physis closes

    • Epide>Epidemiology

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  • Rare cartilage tumour
  • < 1% of all bone tumours
  • Found in 2nd decade with peak at 20 years
  • M:F – 1.5:1
  • Appears in secondary ossification centre
    • Epiphysis of long bones (cf. Enchondromas in meta-diaphysis)
      • Proximal humerus (Codman’s tumour)
      • Around knee
        • Distal femur
        • Proximal tibia
  • On rare occasions seen in
    • Older patients
    • Odd locations such as spine & flat bones

    • Clinical >Clinical Features

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  • Adolescent or young adult
  • Pain & swelling
  • Can restrict ROM of joint
  • Confused with intra-articular pathology
  • Can alter the epiphyseal development in young children

    • Investiga>Investigations

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  • X-ray
    • Well-demarcated lucent defect (ie. radiolucent with sclerotic margin)
    • Epiphyseal in location & eccentric
    • May extend into metaphysis
    • 25-50% have punctate calcification
    • 25% have popcorn or chicken-wire calcification
    • < 10% have periosteal reaction
    • Cortical bone intact or expanded
  • Bone Scan
    • Very hot
  • MRI
    • Oedema seen in surrounding tissues

    • Pathology>Pathology

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  • Gross
    • Gritty/ Greyish pink material
  • Microscopic
    • Highly cellular & undifferentiated tissue
    • Sheets of Chondroblasts
    • Round & Polygonal cells (plump or like fried eggs)
    • Bluish cytoplasm
    • Occasional multinucleated cells of osteoclast type
    • Small areas of cartilaginous matrix & extracellular calcification present
    • Chicken wire calcification
    • Atypical cartilage matrix
    • Stains positive for S100
    • Chondroid Matrix
    • Differentiate from
      • GCT by absence of typical spindle stromal cells of GCT
    • 20% are cystic & haemorrhagic similar histologically to ABC

    • Different>Differential Diagnosis

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  • GCT
  • OCD
  • Brodies abscess
  • Clear Cell Chondrosarcoma
  • Enchondroma
  • Fibrous dysplasia

    • Treatment>Treatment

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  • Difficult to irradicate due to anatomic position without damaging joint or physis
  • Intralesional curettage & bone grafting
    • usual approach
  • Often access through growth plate as patient at or near end of growth
    • Ie. preserve the joint rather than growth plate
  • If recurrence occurs then wide resection procedure of choice

    • Intra-les>Intra-lesional Curettage

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  • Technically more feasible
  • Intra-articular exposure required
  • Local Adjuvant Therapy
    • Phenol
    • Liquid Nitrogen
      • Avoid damage to physis if possible
    • Bone graft
  • Recurrence may occur
  • Usually cured with 2nd curettage

    • Wide Rese>Wide Resection

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  • Lower recurrence rate
  • Usually not possible without loss of function
  • Indicated for 2nd recurrence
  • There is incidence of pulmonary lesions which are rimmed with bone & should be excised

    • Prognosis>Prognosis

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  • The recurrence rate with chondroblastoma alone is 20% at 3 years
  • If the tumor has an aneurysmal component, the risk of recurrence is higher
  • Follow-up care is necessary because recurrence is common
  • Radiographs should be repeated every 6-12 months after excision for ~2 years