Clear cell chondrosarcoma
Clear cell chondrosarcomas represent a chondrosarcoma subtype representing 1-2% of all chondrosarcomas. They are typically low-grade (see chondrosarcoma grading) and get their name from the presence of clear cell chondrocytes which have abundant vacuolated cytoplasm due to the presence of glycogen.
Typically they present in patients in their 3rd to 5th decades, with men being affected twice as often as women (M:F ~ 2:1 ).
Symptoms persist for an average duration of one year, suggesting slow growth of the lesion.
In approximately half of cases conventional chondrosarcomatous elements are also present. Macroscopically haemorrhage and cyst formation are common, and radiographically matrix calcification is uncommon.
The lesion is most often in an epiphyseal location (a contradistinction to the conventional chondrosarcoma which is usually metaphyseal-diaphyseal).
- tubular long bones: 85-90%
- proximal femur: 55-60% (commonest)
- proximal humerus: 10-15%
- distal femur or proximal tibia: 10-15%
On radiographs, clear cell chondrosarcomas are predominantly lytic and expansile.
- endosteal irregularity is not infrequent
- periosteal reaction does not occur.
- soft tissue extension and cortical break are usually seen only if a pathologic fracture occurs.
- low reported incidence of a calcified matrix
- in up to 20% of cases, a peripheral rind of sclerosis is apparent (simulating a benign lesion).
Typically reported signal characteristics on MR imaging include
- T1 - homogeneous intermediate signal intensity
- T1 C+ (Gd) - may show heterogeneous enhancement
- T2 - heterogeneous high signal intensity
Treatment and prognosis
A clear cell chrondrosarcoma is a relatively slow-growing, low-grade malignant tumour. It carries a much better prognosis than a conventional chrondrosarcoma. Because of the relatively benign appearance of the lesion on radiographs, surgical intervention is often delayed. Distant metastases have however been reported in the lung, brain, and bones.
- chondroblastoma - a particular feature of clear cell chondrosarcomas is a predilection for the epiphysis, in which case they mimic chondroblastomas; distinguishing between the two can be difficult (see Chondroblastoma vs. clear cell chondrosarcoma)
The differential diagnosis for bone tumours is dependent on the age of the patient, with a very different set of differentials for the paediatric patient.
- bone-forming tumours
- cartilage-forming tumours
- chondromyxoid fibroma
- fibrous bone lesions
- bone marrow tumours
- other bone tumours or tumour-like lesions
- aneurysmal bone cyst
- benign fibrous histiocytoma
- giant cell tumour of bone
- Gorham massive osteolysis
- haemophilic pseudotumour
- intradiploic epidermoid cyst
- intraosseous lipoma
- musculoskeletal angiosarcoma
- musculoskeletal haemangiopericytoma
- primary intraosseous haemangioma
- simple bone cyst
- impending fracture risk
- 1. Murphey MD, Walker EA, Wilson AJ et-al. From the archives of the AFIP: imaging of primary chondrosarcoma: radiologic-pathologic correlation. Radiographics. 23 (5): 1245-78. doi:10.1148/rg.235035134 - Pubmed citation
- 2. Varma DG, Ayala AG, Carrasco CH et-al. Chondrosarcoma: MR imaging with pathologic correlation. Radiographics. 1992;12 (4): 687-704. Radiographics (abstract) - Pubmed citation