Giant Cell Tumour
Giant cell tumor (GCT) of bone is an aggressive benign tumor. Common age group is 20 – 40 years, more commonly in women. GCT can arise in any bone in body, found in the metaphysis of long bones more commonly around knee joint followed by distal radius, hip, shoulder and pelvis in decreasing frequency.
What is cause of GCT?
Etiology is unknown. They appear to be an extensive proliferation of Osteoclasts (cells which are part of remodeling process in bone), eating away the normal bone architecture. They can present as a small contained tumor or an aggressive type expanding the bone and producing a clinically noticeable swelling. GCT can also rarely (2-5 %) metastasize to lungs, but is not fatal and is treatable.
How is GCT identified?
An individual with GCT presents with pain of involved site, associated or aggravated with movement in early stages within 1-2 months. In the later stages as the tumor expands, pain is noted at rest with a clinically palpable swelling. Occasionally if left untreated, the bone involved may fracture complicating the situation.
A plain radiograph and preferably MRI is performed of affected area followed by Biopsy (Needle preferred). Radiological examination may show an eccentric lytic lesion placed in metaphysis-epiphysis area of long bone with varying destruction of surrounding bone. The tumor when aggressive or diagnosed in late stage may have soft tissue extension. Histopathological examination shows ‘Multinucleated Giant cells’ in abundance.
What are the grades of GCT?
GCT can be classified according to Campanacci Classification. Treatment may vary depending on the stage and location of GCT.
- A) Latent (Grade 1): Well defined, contained lesion with intact surrounding bone/cortex.
- B) Active (Grade 2): Relatively well defined but very thin surrounding bone or cortex.
- C) Aggressive (Grade 3): Indistinct borders, surrounding bone destruction and soft tissue component due to expansion.
How is GCT treated?
Treatment for GCT is primarily by surgery.
Majority of lesions are treated currently by Extended curettage and filling of defect. Extended curettage is a procedure wherein the surgeon clears the cavity of the tumor by opening the capsule and extending the clearance with aid of high speed burr (1-2 mm). This ensures a thorough clearance or curettage or GCT and reduces the rate or tumor recurrence to 10%. Adjuvants such as Phenol or Liquid Nitrogen can also be used to help kill the tumor cells and reduce the recurrence rate locally, but the clinical evidence is not very strong to advocate its use. We currently use Argon Laser beam to burn the wall of cavity and has provided excellent results. The resultant defect can be filled by Bone grafts (Autograft-Fibula, Iliac crest or Allograft-Fibula, either as a filler or support) or by Cement. Utilizing a bone graft provides a more ‘Native or Biological’ reconstruction helping the biomechanics of adjacent joint. Cement is utilized when only the defect needs to be filled and less commonly for structural support.
Several scientific studies suggest that cement usage may have the advantage of identifying a local recurrence early compared to bone graft. The choice of filling the defect is hence individualized based on many factors, especially the stage, location of tumor, proximity to adjacent joint and function it has to perform.
Rarely, a GCT which is Grade 3 or late presentation with adjacent joint destruction may require surgical removal of the tumor with capsule and soft tissue. The defect can be reconstructed with various Limb Salvage options such as arthroplasty, arthrodesis etc.
Giant Cell Tumour Of Distal Femur Treated with extended Curettage and Cementing
Does GCT reappear?
Local recurrence rate of GCT ranges from 10-50 %. The rate is nearly 50 % when only curettage is performed. The use of High speed burr reduces the risk of recurrence to nearly 10 % (with or without the usage of adjuvants). The Local recurrence when diagnosed can again be treated with extended curettage with excellent results. Rarely, a large or multiple local recurrence may need surgical excision and reconstruction by other methods. Radiotherapy is used sparingly in GCT due to risk secondary sarcomatous changes.
Are there any additional treatments available for GCT?
GCT in certain areas such as Pelvis, Sacrum and Spine may not be suitable for primary surgical treatment. A new drug, Denosumab (given intravenously over 2-6 months) is promising, approved by FDA for above mentioned indications and under ongoing clinical trials.
Denosumab can be useful alternative either as definitive treatment or as neo adjuvant drug to solidify the tumor and reduce its size, but indications are not clearly defined yet. Zoledronic acid (4 mg intravenous) has been reported to reduce local recurrence when used intra or post operatively.
However, these drugs are not advocated for routine use in giant cell tumours and have to be used with caution with due consideration to benefits and risks involved.
What is the course of GCT?
GCT is not fatal, even though reports of multiple synchronous occurrences or metastases to lungs have been reported. Lung metastases respond well to Zoledronic acid/Denosumab treatment and rarely need surgical removal. Aggressive monitoring is performed every 3 months for 2 years (Plain radiographs and Chest radiograph/CT of Chest) and thereafter annually.