Imaging Findings :
Findings reveal a destructive lesion involving the lower diaphyseal shaft of the fibula
with cortical erosions and soft tissue swelling.
Diagnosis :
Ewing's sarcoma
Discussion :
Ewing's sarcoma belongs to a group of highly malignant tumours involving bone,
characterised histologically by numerous small round cells. Within this group are included
metastatic neuroblastoma, non-Hodgkins' lymphoma and undifferentiated tumours.
Clinical findings include pain of several weeks' or months' duration and accompanied by
local tender swelling, fever, anaemia and a raised ESR. The majority of patients are
between 5 and 30 years of age.
The lesion is most often found in a long bone, the diaphysis being more commonly affected;
in about 40% of cases, the axial skeleton is involved, particularly the pelvis and ribs.
Metastatic spread occurs early to other bones and lungs.
Imaging Findings :
The lesion is essentially destructive, ill-defined and principally involves the medullary
cavity. Cortical erosions and periosteal reactions occur early, and a periosteal reaction
may perhaps be the only early sign of abnormality. Although the onion-peel lamellar type
of periosteal reaction has been described for this lesion, it is seen infrequently and may
also be noted in other lesions such as osteosarcoma and infection. Codman's triangles are
observed in Ewing's sarcoma, they represent elevation of periosteal new bone at the
margins of cortical erosions. The tumour is highly vascular and shows soft tissue
extension, these features are easily picked up on CT/MRI.
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