Extraskeletal chondrosarcoma

Extraskeletal chondrosarcomas make up only 2% of soft-tissue sarcomas  and only 1% of all chondrosarcomas.

Pathology 

They tend to be of higher grade than run-of-the-mill conventional intramedullary chondrosarcomas, with the majority being of the myxoid (most common) or mesenchymal varieties ³. 

Location

Extraskeletal myxoid chondrosarcomas typically occur in the extremities, with the thigh being most common. They occur at all ages but typically around the age of 50 ³.

Extraskeletal mesenchymal chondrosarcomas on the other hand tend to occur in young adults. They are seen also in the thigh, but also have a predilection for the head and neck, occurring in the meninges, the orbit and even in the brain.

Chondrosarcomas have been reported in most other parts of the body, although with less frequency, including:

• meninges of the brain and spinal cord (most common)
• lower limb (particularly thigh)
• soft tissues of the head and neck
  • orbit
  • larynx
  • sinonasal cavity ⁴
• lung - primary pulmonary chondrosarcoma - very rare 
• solid organs
  • pancreas ²

Radiographic features

Their appearance is the same as that of chondrosarcomas elsewhere (see generic chondrosarcoma article for radiographic features). 

Differential diagnoses

• sarcomas
  • synovial sarcoma
  • malignant fibrous histiocytoma
  • extraskeletal osteosarcoma
• benign lesions
  • myositis ossificans