Conventional intramedullary chondrosarcoma
Conventional chondrosarcoma also known as central chondrosarcoma is the most comon subtype of chondrosarcoma and may be low, intermediate or high grade (see chondrosarcoma grading). They typically occur in the 4th and 5th decades with a slight male predominance 1.5-2.0:1.
At diagnosis it is typically a large mass, usually over 4 cm in diameter. When arising in long bones (most common location, see below) it typically involves more than 50% of the length of the shaft.
Typically chondrosarcomas present with:
- pain: present in 95% of cases, often long standing and worse at night
- palpable mass: 28-82% cases
- pathological fracture: 3-17%
Histologically, the tumor grows as multiple hyaline cartilage nodules with central high water content and peripheral endochondral ossification. This accounts for not only the high T2 MRI signal but also for rings and arcs calcification and popcorn calcification on CT and plain film.
For imaging findings please refer to the article on chondrosarcoma.
- long bones (45%)
- femur (20-35%)
- tibia (5%)
- upper limb, especially proximal humerus (10-20%)
- pelvis (25%)
- ribs (8%)
- spine (7%)
- scapula (5%)
- sternum (2%)
- skull (uncommon)
Enchondroma vs. chondrosarcoma
- Low grade conventional chondrosarcomas can be difficult to distinguish from an enchondroma, as both grow in a nodular pattern and result in scalloping of the inner surface of the cortex. Scalloping of greater than 2/3 of the cortical thickness, cortical breach and soft tissue mass beyond the confines of the bone are useful distinguishing features