Synonyms

• GCT
• giant cell tumour
• osteoclastoma

Category

Bone

Behaviour

Intermediate

Grade

Variable

Gender

Both equally

Tissue of Origin

Bone

Epidemiology

• Intermediate-grade osteolytic lesion
• Peak incidence 2nd-3rd decades
• Primarily around the knee (distal femur and proximal tibia)
• Rare in skeletally immature patients
• H3F3A mutations characteristic

Clinical Features

• Pain and swelling around knee
• Functional impairment
• Pathological fracture possible
• Local recurrence common

Location

• Distal femur (most common)
• Proximal tibia
• Distal tibia
• Rarely other long Bones

Imaging

• Plain radiograph: eccentric lytic lesion extending to articular surface
• MRI: lobulated mass with hemosiderin deposits
• CT: assess cortical breakthrough

Pathology

• Mononuclear stromal cells and multinucleated osteoclast-like giant cells
• H3F3A G34W mutations pathognomonic
• Fibroblastic and osteoclastic elements
• Intermediate-grade appearance

Genetics

• H3F3A mutations (G34W/G34R) in >95%
• Somatic mutations (not germline)

Treatment

• Wide surgical excision: standard of care
• Curettage with local adjuvants (phenol, cement) for marginal lesions
• Denosumab: for unresectable, metastatic, or recurrent disease

Prognosis

• 10-50% local recurrence after surgery
• Rare metastases to lungs (3%)
• Malignant transformation rare (1%)

Key Points

• H3F3A mutations define giant cell tumour
• Typically epiphyseal around knee
• High recurrence risk requires close Follow-up
• Denosumab effective for inoperable disease

Workup - Blood Tests

FBC, U&E, LFTs

Workup - Local Imaging

• Plain radiograph
• MRI to assess extent and soft tissue involvement
• CT to characterise bone

Workup - Biopsy

Core biopsy: H3F3A mutation testing for confirmation

Workup - Staging

• CT chest: metastatic screening
• No formal staging

Workup - Other

• Orthopedic oncology consultation
• Discuss denosumab for recurrent/unresectable disease

Follow-up Summary

• Post operative visit first 6 weeks
• Year 1 - 3-6 monthy clincical examination and x-ray of primary site +/- CXR
• Year 3 - 6 monthy clincical examination and x-ray of primary site +/- CXR
• Discharge at 3 years