Presentation
Right shoulder, ankle and knee pain.
Patient Data
Dense sclerosis of the medial right clavicle (hyperostosis).
AP and lateral radiographs of the right knee show diffuse cortical thickening; a thick, lamellated periosteal reaction, and hyperostosis.
Hyperostosis of the lateral malleolus.
Two years after the initial examinations, the patient presented with a persistent right knee effusion and periarticular swelling.
Extensive cortical thickening of the distal diaphysis of the femur, extending into the metaphyseal region, particularly medially. There is a mild degree of edema within the bone with associated enhancement. The adjacent soft tissues show a mild degree of enhancement. There is enhancement of the synovium consistent with synovitis. The marrow signal remains intact. Moderate to large sized joint effusion is present. Mild loss of cartilage over the medial femoral condyle anteriorly and an area of defect seen within the medial femoral condyle anteriorly and posteriorly.
Case Discussion
The patient presented with non-specific pain and skin lesions at time point zero and a diagnosis of SAPHO was made. Two years later, the patient re-presented with pain and swelling of the right knee joint and a mildly elevated C-reactive protein 10 mg/L (normal: <5 mg/L). The follow-up radiographs of the right knee were consistent with an underlying aggressive process.
Joint aspiration showed no organisms.
Specimen: synovial fluid
Crystals: no birefringent crystals seen
Gram Stain: no organisms seen
Leukocytes: 1+
Erythrocytes: scant
Culture: No growth
MRI and clinical assessment were in agreement that the patient had presented for the second time with an acute on chronic episode of sterile osteomyelitis with associated synovitis.
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