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Updated: Aug 7, 2026

Simultaneous Detection of Different Antibody Classes in a Multiplexed Serological Test
Published on: July 14, 2023
[Borrelia as a differential diagnosis to monoarthritis]
Marie Louise Isaksen1, Steen Bærentzen2, Carsten Schade Larsen1
1Infektionssygdomme, Aarhus Universitetshospital.
Abstract:
In this case report, a young woman presented with recurring knee monoarthritis. Arthroscopy revealed synovitis, and histology showed chronic plasma cell-dominated inflammation. A positive serum-borrelia IgG titre supported the suspicion of Lyme arthritis despite a negative specific Borrelia PCR result on a paraffin-embedded synovial biopsy. Treatment with phenoxymethylpenicillin, initiated more than two years after symptom onset, resulted in rapid and near-complete remission. The case underscores the diagnostic challenges of Lyme arthritis and the importance of considering the diagnosis in mono- or oligoarthritis.
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