OSTEOCLASTOMA (GIANT CELL TUMOUR)
OSTEOCLASTOMA (GIANT CELL TUMOUR)
- Giant cell tumour (GCT) is a common bone tumour with variable growth potential.
- Though generally classified as benign, it tends to recur after local removal.
- Frankly malignant variants are also known.
- Malignancy in GCT- Osteosarcoma or Malignant Fibrous Histiocytoma or Fibrosarcoma.
PATHOLOGY
- The cell of origin is uncertain.
- Microscopically, the tumour consists of undifferentiated spindle cells, profusely interspersed with multi-nucleate giant cells.
- The tumour stroma is highly vascular.
- These giant cells were mistaken as osteoclasts in the past, hence the name osteoclastoma.
CLINICAL FEATURES
- The tumour is seen commonly in the age group of 20-40 years i.e., after epiphyseal fusion.
- The bones affected commonly are those around the knee i.e., lower-end of the femur and upper-end of the tibia.
- Lower-end of the radius is another common site.
- The tumour is located at the epiphysis.
- It often reaches almost up to the joint surface.
- Common presenting complaints are swelling and vague pain.
- Sometimes, the patient, unaware of the lesion, presents for the first time with a pathological fracture through the lesion.
- Examination reveals a bony swelling, eccentrically located at the end of the bone.
- Surface of the swelling is smooth.
- There may be tenderness on firm palpation.
- A characteristic ‘egg-shell crackling’ is often not elicited.
- The limb may be deformed if a pathological fracture has occurred.
DIAGNOSIS
- GCT is one of the common cause of a solitary lytic lesion of the bone, and must be differentiated from other such lesions.
Following are some of the characteristic radiological features of this tumour:
- A solitary, may be loculated, lytic lesion.
- Eccentric location, often subchondral.
- Expansion of the overlying cortex (expansile lesion).
- ‘Soap-bubble’ appearance – the tumour is homogeneously lytic with trabeculae of the remnants of bone traversing it, giving rise to a loculated appearance.
- No calcification within the tumour.
- None or minimal reactive sclerosis around the tumour.
- Cortex may be thinned out, or perforated at places.
- Tumour usually does not enter the adjacent joint.
TREATMENT
- Wherever possible, excision of the tumour is the best treatment.
- For sites like the spine, where excision is sometimes technically not possible, radiotherapy is done.
- Following treatment methods are commonly used:
a) Excision: This is the treatment of choice when the tumour affects a bone whose removal does not hamper with functions e.g., the fibula, lower-end of the ulna etc.
b) Excision with reconstruction: When excision of a tumour at some site may result in significant functional impairment, the defect created by excision is made up, usually partially, by some reconstructive procedure.
- For example, in tumours affecting the lower-end of femur, the affected part is excised en bloc, and the defect thus created made up by one of the following methods:
Arthrodesis by the Turn-o-Plasty procedure:
- In this technique, the required length of the tibia is split into two halves.
- One half is turned upside down and fixed with the stump of the femur left after excising the tumour.
- A similar procedure can be used for a tibial lesion by taking half of the femur.
Arthrodesis by bridging the gap by double fibulae , one taken from same extremity and the other from the opposite leg.
Arthroplasty: In this procedure, the tumour is excised, and an attempt is made to reconstruct the joint in some way.
- This can be carried out using an autograft (patella to substitute the articular defect), allograft (replacing the defect with the preserved bone of a cadaver), or an artificial joint (prosthesis).
c) Curettage with or without supplementary procedures: Curettage performed alone has the disadvantage of a high recurrence rate.
d) Amputation: For more aggressive tumours, or following recurrence, amputation may be necessary.
e) Radiotherapy: It is the preferred treatment method for GCT affecting the vertebrae.
- Treatment for GCT at commoner sites is as given in Table
| Site | Treatment of choice |
| Lower end of femur | Excision with Turn-o-Plasty |
| Upper end of tibia | Excision with Turn-o-Plasty |
| Lower end of radius | Excision with fibular grafting |
| Lower end of ulna | Excision |
| Upper end of fibula | Excision |
Exam Important
- Giant cell tumor is an epiphyseal tumor.
- GCT seen commonly in the age group of 20-40 years
- Soap bubble appearance on X-ray is seen in Giant cell tumor.
- GCT malignant component is Mononuclear cells.
- Giant cell variants (Tumor with giant cells):
- Brown tumor of hyper parathyroidism
- Aneurysmal bone cyst (closest)
- Non-ossifying fibroma (commonest)
- Fibrosarcoma
- Osteoclastoma is treated with Joint replacement, Excision, Curettage, Arthrodesis.
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