Case contributed by Jane McEniery
Diagnosis certain


Knee pain and swelling. Exclude fracture.

Patient Data

Age: 10 years
Gender: Female

AP and lateral XR of the right knee shows an ill-defined lesion within the right distal femoral diaphysis and metaphysis with: 

  • wide zone of transition
  • mixed density of lysis/sclerosis
  • cortical destruction and aggressive periosteal reaction
  • soft tissue mass anteriorly 
  • no associated pathologic fracture

Aggressive bone lesion:

  • T1 hypointense, T2 hyperintense, heterogeneously enhancing
  • centered in the right distal femoral diaphysis and extending into the epiphysis with a circumferential subperiosteal soft tissue mass
  • epiphyseal component involves the articular cortex in the intercondylar region
  • joint effusion and muscular edema
  • no pathological fracture
  • no skip lesions

Case Discussion

Osteosarcoma was confirmed histologically. On imaging, the differential diagnosis also includes Ewing sarcoma. 

Case contributed by Dr Gillian Long

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