Chondrosarcomas are malignant cartilaginous tumours that account for 20 - 27% of all primary malignant bone tumours.
Typical presentation is in the 4th and 5th decades and there is a slight male predominance - M : F of 1.5 - 2 : 1.
Patients usually present with pain, pathological fracture, a palpable lump or local mass effect. Hyperglycaemia : can occur as a paraneoplastic phenomenon.
The histology of chondrosarcomas can differ according to their sub type (see below). In general these tumours are multilobulated (due to hyaline cartilage nodules) with central high water content and peripheral enchondral ossification. This accounts not only for the high T2 MRI signal (see below) but also for rings and arcs calcification or popcorn calcification.
Chondrosarcomas are divided into 3 (sometimes 4) grades based primarily on cellularity. (see Chondrosarcoma grading)
Chondrosarcomas are either primary, arising de novo, or secondary and arise from a pre-existent cartilagenous mass : see secondary chondrosarcoma.
- conventional intramedullary chondrosarcoma (or central chondrosarcoma) : low, intermediate or high grade (see chondrosarcoma grading)
- juxtacortical chondrosarcoma : low, intermediate or high grade
- clear cell chondrosarcoma
- myxoid chondrosarcoma : usually intermediate grade
- mesenchymal chondrosarcoma : usually high grade
- extraskeletal chondrosarcoma
- dedifferentiated chondrosarcoma
Arising from pre-existing cartilagenous lesions :
- solitary osteochondroma
- hereditary multiple exostoses (also known as diaphyseal aclasis)
- long bones : 45% (the reason is because the cartilage is more abundant in the long, tubular bones).
- pelvis : 25% especially around the triradiate cartilage
- ribs : 8%
- patients often younger than at other sites
- anterior ribs / costochondral junction
- spine : 7%
- greater male predominance 2 - 4 : 1
- thoracic most common
- location :
- posterior elements and vertebral body 45%
- posterior elements only 40%
- vertebral body only 15%
- scapula : 5%
- sternum : 2%
- head and neck (including cervical spine) : 6-7%
- craniofacial : 2% (see chondrdosarcoma of the skull of base)
- hands and feet : rare c.f. enchondromas
Imaging findings vary somewhat with different sub types but do have some general features. Below are typical imaging appearances which are best demonstrated by conventional chondrosarcomas.
In general chondrosarcomas are large masses a the time of diagnosis, usually over 4cm in diameter and over 10cm in 50% of cases.
- lytic : 50%
- calcification(s) : 60 - 78% (rings and arcs calcification or popcorn calcification)
- endosteal scalloping : affecting more than two thirds of the cortical thickness (c.f. less than 2/3 in enchondromas)
- moth eaten appearance or permeative appearance in higher grade tumours (see chondrosarcoma grading), e.g myxoid, dedifferentiated and mesenchymal chondrosarcomas.
- cortical remodelling, thickening and periosteal reaction are also useful in distinguishing between an enchondroma and low grade chondrosarcoma (see enchondroma vs. low grade chondrosarcoma)
Typically chondrosarcomas demonstrate increased uptake on bone scan, seen in over 80% of cases, and usually the uptake is quite intense. This is useful in helping to distinguish a low grade chondrosarcoma from an enchondroma as the later has increased uptake in only 21% of cases, and usually to a lesser degree. (see enchondroma vs. low grade chondrosarcoma)
The features seen on CT are the same as on plain film, but are simply better seen.
- 94% of cases demonstrate matrix calcificaiton, c.f. 60 - 78% on plain film.
- endosteal scalloping
- cortical breach, seen in 88% of longbone chondrosarcoma, c.f. only 8% of enchondromas
- soft tissue mass : density increases with increased grade of tumour do to increased cellularity
- heterogenous contrast enhancment
T1 : low to intermediate signal
- iso to slightly hyper intense c.f muscle
- iso to slightly hypo intense c.f grey matter (see chondrosarcoma of the base of skull)
- T2 : very high intensity in non mineralised / calcified portions
- gradient echo / SWI : blooming of mineralised / calcified portions
T1 C+ (Gd) :
- most demonstrate heterogeneous moderate to intense contrast enhancement.
- enhancement can be septal and peripheral rim-like corresponding to fibrovascular septation between lobules of hyaline cartilage
Treatment and prognosis
Prognosis varies with both grade and location. In general:
- grade 1 : 90% 5 year survival
- grade 3 : 29% 5 year survival
- long bones have a better prognosis than axial skeleton
This article is in need of some more references!
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- 1. Dähnert W. Radiology review manual. Lippincott Williams & Wilkins. (2003) ISBN:0781738954. Read it at Google Books - Find it at Amazon
- 2. Meyers SP, Hirsch WL, Curtin HD et-al. Chondrosarcomas of the skull base: MR imaging features. Radiology. 1992;184 (1): 103-8. Radiology (abstract) - Pubmed citation
- 3. Varma DG, Ayala AG, Carrasco CH et-al. Chondrosarcoma: MR imaging with pathologic correlation. Radiographics. 1992;12 (4): 687-704. Radiographics (abstract) - Pubmed citation
- 4. 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
- 5. Geirnaerdt MJ, Hogendoorn PC, Bloem JL et-al. Cartilaginous tumors: fast contrast-enhanced MR imaging. Radiology. 2000;214 (2): 539-46. Radiology (full text) - Pubmed citation
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