Giant Cell Tumor (GCT)

Common Sites

• Most common: Knee region (distal femur, proximal tibia)

• Also seen in: Distal radius, proximal humerus, sacrum (most common axial site)

 Clinical Presentation

• Persistent pain (most common)

• Joint swelling, limited motion, or pathological fracture (5–10%)

• Palpable mass (if soft tissue extension exists)

• No constitutional symptoms

 Imaging Features

X-ray:

• Eccentric, lytic lesion

• No sclerotic rim, no calcification

• Cortical expansion without periosteal reaction

• Wide transition zone in fibula/ulna

• Aggressive signs: Geographic destruction, soft tissue mass, fluid-fluid levels (if secondary ABC)

CT:

• Detects lung metastases, evaluates axial involvement and trabecular pattern

MRI:

• T1: Hypo- to isointense

• T2: Hyperintense, heterogeneous

• Shows soft tissue extension and blooming on GRE (hemosiderin)

 Campanacci Classification

Used as a surgical guide.

 Differential Diagnosis

• Chondroblastoma: Epiphyseal, sclerotic rim, surrounding bone marrow oedema

• Aneurysmal Bone Cyst (ABC): May co-exist, lacks soft tissue mass

• Brown Tumour: Consider if high PTH

    Treatment

Surgical Management (Extremities)

• Intralesional curettage + adjuvant (phenol, ethanol, cryotherapy, argon gas, high-speed burr) + PMMA or graft
  PMMA advantages: Exothermic necrosis, easier recurrence detection
  Risks: Subchondral damage → early osteoarthritis

• Wide resection: Indicated in Campanacci 3, distal ulna/proximal fibula

• Denosumab (pre-op): Used to shrink tumour for limb-salvage surgery in Campanacci 3

 Management of Pelvic & Axial GCBTs

• Surgery carries high local complication risk

• Grade 1–2: Intralesional resection after radioembolization

• Grade 3:
  If feasible → Wide resection ± radioembolization
  If unresectable → Denosumab alone

• Radiotherapy: Only for inoperable cases (malignant transformation risk)

  Medical Therapy

Denosumab (RANKL inhibitor):

• Pre-op or in inoperable patients

• Avoid in Grade 1–2: Can reduce curettage efficacy and increase recurrence

• Risks: Malignant transformation with long-term use, osteonecrosis of jaw

Bisphosphonates (e.g., zoledronic acid):

• Reduces tumour size

• Side effects: ONJ, atypical femur fracture, oesophagitis, hypo-/hypercalcemia

 Metastasis & Complications

• Lung metastases: Typically indolent; metastasectomy for progressive disease

• Recurrence: 20–50% within 3 years, higher in axial/distal radius sites

• Malignant transformation: Rare but severe (e.g., UPS or osteosarcoma, linked to denosumab)

• PMMA-induced osteoarthritis due to chondral necrosis

 References

• Siegel, G. W., & Biermann, J. S. Orthopaedic Knowledge Update®: Musculoskeletal Tumors 5

• Kang, H. S., et al. Oncologic Imaging: Bone Tumors, Springer

• Choi, J. H., & Ro, J. Y. 2020 WHO Classification of Bone Tumors

• Bayram, S., et al. EFORT Open Rev, 2024;9(3):181–189