PMC8137287_01
Anteroposterior and lateral knee radiographs at presentation (a, b) and 15 days later (c, d) show interval progressive medullary-based eccentric lytic change with a wide zone of transition, aggressive (Codman's triangle) periosteal reaction (arrowheads), and subtle cortical deformity (arrow).
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She and her daughter were referred to her local emergency department where radiographs of the patient's left knee were conducted and were read as unremarkable with no signs of trauma (Figure 1). Given concern for the persistent pain and antalgic gait, repeat radiographs of the left knee were also ordered by the orthopedist and showed aggressive poorly defined lytic lesion centered within the left distal femur metadiaphysis extending up proximally 6 cm superiorly from the metaphysis with associated interrupted superior periosteal involvement (Figure 1).
Magnetic resonance imaging (MRI) of the thighs. Coronal T1-weighted (a) and fluid-sensitive (b) large-field-of-view images confirm a marrow replacement process centered within the left distal femoral metaphysis (star) with extraosseous extension (arrowheads) and proximal marked peritumoral bone marrow edema-like signal (arrow).
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Contrast-enhanced MRI examination showed a enhancing mass centered in the distal femoral metaphysis approximately 7 cm in craniocaudal dimension with aggressive periosteal involvement (Figure 2).
Postoperative anteroposterior radiograph shows resection of the distal femur with Van Nes rotationplasty.
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Postoperative radiographs have demonstrated appropriate healing of the rotationplasty (Figure 3).