Conventional intramedullary chondrosarcoma

Conventional chondrosarcoma (aka central chondrosarcoma) is the most comon sub type of chondrosarcoma and may be low, intermediate or high grade (see chondrosarcoma grading). They typically occur in the 4^th and 5^th decades with a slight male predominance 1.5 - 2.0 : 1.

Presentation

At diagnosis it is typically a large mass, usually over 4cm 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 %

Pathology

Histologically, the tumour grows as multiple hyaline cartilage nodules with central high water content and peripheral enchondral ossification. This accounts for not only the high T2 MRI signal but also for rings and arcs calcification and popcorn calcification on CT / plain film. 

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. (see Enchondroma vs. chondrosarcoma) 

Imaging findings

For imaging findings please refer to chondrosarcoma article. 

Location

• 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