case_images: PMC3270528_01
case_images: Urgent MRI of the right lower limb; T1 weighted (left), T2 weighted (right). A large (approx. 15 cm), oval, smoothly defined heterogenous mass with a large necrotic centre is clearly visible behind the lower femur (white arrows). There is also an area of altered signal within the femur itself involving the condyle, suggestive of bony metastasis (white arrowheads). The likely diagnosis is malignant peripheral nerve sheath tumor (MPNST) with a differential diagnosis of lymphoma or other soft tissue sarcoma. The character and distribution of the pain could signify a sciatic nerve origin.
case_images: CRIM2012-479632.001.jpg
case_images: PMC3270528_01_CRIM2012-479632.001.jpg
case_images: fig1
case_images: He was referred back to Orthopaedics and an urgent MRI confirmed an oval, smoothly defined heterogenous mass in addition to signal changes in both right and left femurs, most likely representing metastatic foci (Figure 1).