Achy Leg in a Child
Try out this paediatric case and test your clinical knowledge. The answers are at the bottom.
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This is an AP image of the R knee including the distal femur and proximal tibia + fibula.
There is an extensive sclerotic disease in the distal femur, with the formation of a Codman’s triangle periosteal reaction.
The disease is sclerotic (appears whiter than normal on XR) as osteosarcoma is a cancer of primitive osteoblasts, the cells responsible for bone formation. As such, aberrant multiplication of these cells in cancer produces malignant osteoid which leads to aberrant bone formation and appears whiter on XR – sclerotic. This contrasts with Ewing’s sarcoma, the other major malignant bone tumour in children, which usually presents with a lytic (bone destructive) lesion on XR. Codman’s triangle refers to the area on the medial aspect of the femur where hypoxic changes induced by the tumour leads to aberrant bone formation by the periosteum which is then broken through by the tumour invading into the surrounding tissues, forming a triangle like structure on X-ray.
Image 1: Case courtesy of Assoc Prof Frank Gaillard, <a
href=”https://radiopaedia.org/?lang=gb”>Radiopaedia.org</a>. From the case <a
Dr Amol Joshi
University of Cambridge