8. Giant cell tumours

Question 1

Types of giant cell tumours

Answer 1

1. Giant cell tumour

2. Giant cell reparative granuloma

Question 2

Definition of giant cell tumours

Answer 2

Benign but locally aggressive tumour

Question 3

Epidemiology of giant cell tumours

Answer 3

1. 4-5% of all primary bone tumours
2. 3rd to 5th decades, more common in Oriental countries
3. Male : female = 1 : 1.2

Question 4

Morphology of giant cell tumours

Answer 4

1. Grossly:
   - Sites affected:
   i. Long tubular bones, knee (especially distal femur followed by proximal tibia), distal radius
   ii. Epiphyseal or metaphyseal location
   - Often accompanied by aneurysmal bone cyst
   - Beefy hemorrhagic appearance
2. Histologically:
   - Large numbers of osteoclast-like giant cells (50-100 nuclei)
   - Background of epithelioid to spindle shaped mononuclear cells which may be mitotically active & can show varying degrees of cytologic atypia
   - Nuclei of stromal cells are identical to that of the giant cells

Question 5

Clinical features of giant cell tumour

Answer 5

1. X-ray findings:
   - Multiloculated lytic lesion without sclerosis
   - Epiphyseal or metaphyseal location
2. Treatment:
   - Curettage (most common form of treatment)
   - Complete en bloc excision may be necessary in some
3. Prognosis:
   - Recurrence rate of 20-30% with curettage
   - Malignant transformation (to fibrosarcoma or osteosarcoma) very rare

Question 6

Definition of Giant cell reparative granuloma

Answer 6

A misnomer as it does not contain true granulomas; believed to be a reactive/reparative process, even though there is frequently no history of trauma; locally aggressive but has no malignant potential

Question 7

Epidemiology of giant cell reparative granuloma

Answer 7

1. 1st & 2nd decades of life (for jaw involvement); 2nd & 3rd decades (for hand & feet involvement)
2. Male : female = 1 : 2

Question 8

Morphology of giant cell reparative granuloma

Answer 8

1. Grossly:
   - Sites affected:
   i. Most common: jaw bones (maxilla > mandible)
   ii. Small tubular bones of hand & feet
2. Histologically:
   i. Connective tissue stroma with small oval & spindly mononuclear cells
   ii. Mixed uneven clusters of multinucleated (5-40 nuclei) giant cells
   iii. Hemorrhage, hemosiderin laden macrophages
   iv. Reactive bone formation
   v. No pleomorphism or mitotic figures