A 28-year-old woman presents with a 6-month history of progressive swelling and pain in the left knee. Plain radiographs show an eccentric, lytic lesion in the distal femur extending to the articular surface with a soap-bubble appearance. MRI confirms a lesion measuring 4 cm × 3 cm with heterogeneous signal intensity. A biopsy confirms giant cell tumor of bone. The lesion is intra-articular and extends to the subchondral bone. What is the most appropriate next step in management?

Explanation

## Clinical Context This patient has a giant cell tumor (GCT) of bone with classic features: eccentric location, distal femur, soap-bubble appearance on imaging, and intra-articular extension to the subchondral bone. The tumor is large but not locally aggressive enough to warrant amputation, and GCT is chemotherapy-resistant. ## Management Principles for GCT **Key Point:** Intralesional curettage with local adjuvants is the gold standard for GCT of bone, even with intra-articular extension, because: 1. GCT is benign (though locally aggressive) 2. Wide excision is reserved for recurrent or unresectable lesions 3. Adjuvants (phenol, liquid nitrogen, hydrogen peroxide) reduce recurrence rates from 50% to 10–15% 4. Bone grafting restores structural integrity and prevents pathological fracture **High-Yield:** The location (distal femur, intra-articular) and size (4 cm) do NOT mandate wide excision. Intralesional approach preserves joint function and is the standard of care for primary GCT. ## Why Intralesional Curettage Works | Feature | Intralesional Curettage | Wide Excision | |---------|------------------------|---------------| | **Indication** | Primary GCT, resectable lesion | Recurrent GCT, pathological fracture | | **Recurrence rate** | 10–15% (with adjuvants) | 0–5% (but morbidity higher) | | **Functional outcome** | Excellent (joint preservation) | Poor (joint loss, arthritis) | | **Bone loss** | Minimal | Significant | **Clinical Pearl:** Even though this tumor extends to the subchondral bone and is intra-articular, intralesional curettage with adjuvants is still preferred because it allows joint salvage. Wide excision would require distal femoral replacement or arthrodesis, causing significant morbidity in a young patient. ## Adjuvant Options - **Phenol (5%):** Chemical cauterization, reduces recurrence - **Liquid nitrogen:** Cryotherapy, most effective but risk of thermal necrosis - **Hydrogen peroxide:** Mechanical ablation, lower recurrence than curettage alone **Mnemonic — GCT Management Ladder:** **ICCW** - **I**ntralesional curettage + adjuvants (first-line) - **C**hemotherapy (NOT effective for GCT; avoid) - **C**ontour wide excision (for recurrence or pathological fracture) - **W**ide excision with reconstruction (for unresectable or multiply recurrent lesions)