ESR and CRP were within normal limits.
Initial plain radiography of her left knee Case Photo #1 showed a well-positioned total knee replacement with no evidence of loosening. An ill-defined radiolucent lesion was seen in the supracondylar femur just proximal to and abutting her prosthesis. A follow-up CT scan without contrast Case Photo #2 showed a lytic lesion in the distal femur. corresponding to the radiolucent lesion seen on plain films. MRI with contrast revealed a heterogeneously enhancing, aggressive-appearing lytic lesion in the distal femoral metaphysis extending to the femoral component of the knee arthroplasty. There was evidence of cortical destruction anterolaterally with minimal extraosseous extension. CT chest/abdomen/pelvis revealed no evidence of metastatic disease.
She was referred to orthopedic oncology and a bone biopsy was consistent with spindle cell sarcoma and possible leiomyosarcoma.
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