Presentation
Persistent left knee pain not responding to simple analgesia. No past medical history.
Patient Data
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Lucent expansile lesion in the lateral femoral metaphysis with cortical thinning and breech.
No periosteal reaction.
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Lucent expansile lesion in the lateral femoral epiphysis and metaphysis with cortical breach.
It exhibits intermediate T1 and high T2 signal with mild contrast enhancement.
Small joint effusion.
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High tracer uptake in the distal femur corresponding with the other modalities.
CT of the chest, abdomen and pelvis identified a renal mass.
Subsequent biopsy of the femoral lesion indicated a renal cell carcinoma metastasis.
Case Discussion
A common site of metastasis of renal cell carcinoma is the skeleton, giving rise to lytic expansile metastases.
On occasion, the first presentation (presenting symptoms) may be from a bony metastasis. In this case, the lesion was thought to initially represent a primary bone lesion, which is within the differential.
Solitary bone lesions may be broadly divided into aggressive and non-aggressive from their appearances on plain film.