Chondrosarcoma is the second most common primary, non-haematological, bone malignancy (after osteosarcoma).
Epidemiology
Chondrosarcoma is uncommon, and unlike the other malignant bone tumours tends to affect older individuals (over 50). It is slightly more common in males but not to the extent seen in osteosarcoma and PNET. Most cases are primary; a small number are related to incident conditions.
Aetiology and Pathogenesis
Aetiology and pathogenesis are unknown; some genetic syndromes (Ollier syndrome) have a high incidence of chondrosarcoma but accounts for < 5% of cases. Rarely, chondrosarcoma may arise from a benign chondroma.
Natural History
Chondrosarcomas often arise in the pelvis but can develop in any bone. They are usually less aggressive than other bone sarcomas and symptoms develop over months and years instead of weeks. Metastasis is rare.
Clinical Presentation
Pain is the usual presenting symptom; alternatively the tumour may be found incidentally on imaging. Signs are localise to the involved bone. Imaging appearances are difficult as most chondrosarcomas resemble benign chondroma. The most common features are of central lucency with expansion and thickening of the overlying cortex.
Tumour Features
Macroscopically, chondrosarcoma appears significantly different to the other bone tumours with a translucent, white or blue appearance on the cut surface.
Microscopically, chondrosarcoma can be divided into three grades:
- Grade 1 tumours have moderate cellularity and no mitoses (85% of cases)
- Grade 2 tumours have occasional mitoses, increased cellularity and pleomorphism (12% of cases)
- Grade 3 tumours have frequent mitoses and significant pleomorphism (< 3% of cases)
Staging
Staging is through the TNM system. The latest edition (7th):
| T Stage | Description |
|---|---|
| T1 | < 8 cm in maximum dimension |
| T2 | > 8 cm in maximum dimension |
| T3 | Discontinuous tumours in the same bone |
| N Stage | Description |
|---|---|
| N1 | Nodal metastases |
| M Stage | Description |
|---|---|
| M1a | Lung metastases |
| M1b | Other distant metastases |
Grade was described in the "Tumour Features" section above.
| Stage | T | N | M | Grade |
|---|---|---|---|---|
| IA | T1 | N0 | M0 | Low |
| IB | T2 | N0 | M0 | Low |
| IIA | T1 | N0 | M0 | High |
| IIB | T2 | N0 | M0 | High |
| III | T3 | N0 | M0 | Any |
| IVA | Tany | N0 | M1a | Any |
| IVB | Tany | N1 Nany |
Many M1b |
Any |
