Journal List > J Rheum Dis > v.22(1) > 1064232

Park, Kim, Seong, Ha, Nam, Lee, Kim, Yang, and Kang: Knee Synovitis Mimicking a Septic Arthritis


Synovitis is the inflammation of the synovial membrane with unknown etiology which occurs in association with autoimmune inflammatory arthritis, mainly in rheumatoid arthritis. Synovitis manifesting as rapidly progressing monoarticular or pauciarticualr symptoms could make early diagnosis difficult, thus it could be misdiagnosed as other forms of arthritic diseases. We experienced a rare case of knee joint synovitis which initially manifested as mimicking a septic arthritis. A 58-year-old-male patient underwent renovascular embolization due to retroperitoneal hemorrhage which was developed after renal biopsy. Suddenly, the patient's left knee joint became swollen rapidly with redness and tenderness. Moreover, his right knee also became inflamed. Surgical irrigation and intravenous antibiotics had never worked on his knee joint inflammation, however administration of intermediate dose of steroid could decrease inflammatory signs dramatically. Synovitis in a large joint could be mistaken as a septic arthritis, delaying the right diagnosis. Thus, we report this case with literature review.


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Figure 1.
(A) The patient's left knee joint was swollen with local heat. His right knee joint was also swollen, but less obvious compared to the left side. (B) Total 60 mL of yellow, turbid synovial fluid was aspirated from the left knee joint. (C) The knee x-ray showed only soft tissue swelling around the knee joint.
Figure 2.
Knee magnetic resonance imaging showed large amount of joint effusion with synovial enhancement (arrows) on T1-weighted image in both right (A) and left (B) knee joint.
Figure 3.
Left knee joint gray scale ultrasound showed highly proliferated synovium filling the suprapatellar bursa (A). Power Doppler signals were detected along the marginal areas of highly proliferated synovium (B).
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