Synonyms

• Codman tumour
• epiphyseal chondromatous giant cell tumour

Category

Bone

Behaviour

Benign

Gender

Male

Tissue of Origin

Cartilage

Epidemiology

• Rare, 1% of primary Bone tumours
• Peak incidence 2nd decade (adolescence)
• Male predominance (2:1)
• One of the few epiphyseal tumours

Clinical Features

• Joint pain (often mistaken for arthritis)
• Effusion of adjacent joint
• Restricted range of motion
• Tenderness over epiphysis

Location

• Epiphysis of long Bones - virtually always
• Distal femur, proximal tibia, proximal humerus most common
• Greater trochanter and humeral head
• Rarely small Bones of hands/feet (apophyseal location)

Imaging

• Well-defined lytic epiphyseal lesion with sclerotic margin
• Stippled calcification in 50%
• MRI: extensive Bone marrow and soft tissue oedema (may mimic infection)
• Bone scan: markedly hot - out of proportion to lesion size

Pathology

• Chondroblasts with 'chicken-wire' calcification
• S100-positive chondroblasts with grooved/coffee-bean nuclei
• Scattered osteoclast-type giant cells
• H3F3B K36M mutation in >90%

Genetics

• H3F3B K36M mutation - Highly specific and diagnostically useful
• Distinct from GCT which has H3F3A G34W mutation
• Simple karyotype

Treatment

• Curettage and Bone grafting
• Extended curettage with adjuvants (phenol/liquid nitrogen) to reduce recurrence
• Physis-sparing approach in skeletally immature patients
• Denosumab: emerging role for unresectable cases

Prognosis

• Excellent - Malignant transformation exceedingly rare
• Recurrence rate 10–20% after curettage
• Pulmonary implants (Benign) described - not true metastasis
• Growth disturbance possible if physis damaged

Key Points

• One of the few truly epiphyseal Bone tumours (along with GCT and clear cell chondrosarcoma)
• H3F3B K36M IHC is Highly sensitive and specific for diagnosis
• Extensive perilesional oedema on MRI is characteristic and can mislead towards aggressive diagnosis
• Benign pulmonary implants documented - do not require treatment

Workup - Blood Tests

No blood tests required

Workup - Local Imaging

• Plain radiograph
• CT - assesses internal calcifications and cortical integrity
• MRI

Workup - Biopsy

• Biopsy if imaging uncertain
• Histology: primitive chondroblasts with chondroid matrix; chicken wire calcifications

Workup - Staging

No staging required

Follow-up Summary

• Post-op visit at 6 weeks; plain X-ray + MRI of primary site at 3 months post-op
• Year 1–2: 6-monthly clinical review + plain X-ray of primary site
• Year 3–5: Annual review; imaging only if symptomatic
• Discharge at 5 years if no local recurrence
• Benign pulmonary implants: if found incidentally - CT chest for characterisation; no treatment required if stable
• Physeal monitoring in skeletally immature patients - assess for growth disturbance at each visit