PMC3964674_01
Plain lateral x-ray of the knee showing prepatellar soft tissue swelling; no obvious bony lesion
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fig1
An x-ray showed a large prepatellar swelling but no obvious bony pathology (Fig 1).  
Lateral x-ray of the knee showing a focal lytic lesion in the patella with overlying soft tissue swelling and minor periosteal reaction; features consistent with a Brodie's abscess
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fig2
Further knee radiography showed a central nidus of necrotic bone in the patella (Fig 2).
T1 weighted magnetic resonance imaging showing a 16mm x 12mm well defined lucency with central calcific densities, suggesting chronic osteomyelitis with sequestrum
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fig3
Magnetic resonance imaging (MRI) confirmed osteomyelitis (Fig 3).