Chondroblastoma

  • A benign tumour of cartilaginous origin with a predilection for the epiphysis in skeletally immature patients

Definition

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

Epidemiology

  • 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 Features

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

Investigations

  • 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

Chondroblastoma, histology of chondroblastoma with secondary aneurysmal bone cyst change
Histology of chondroblastoma with secondary aneurysmal bone cyst change. Image by Sarahkayb, Wikimedia Commons, CC BY-SA 4.0.
  • 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

Differential Diagnosis

Treatment

  • Difficult to eradicate 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-lesional Curettage

  • 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 Resection

  • 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

  • The recurrence rate with chondroblastoma alone is 20% at 3 years
  • If the tumour 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

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.