{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,14]],"date-time":"2026-08-14T11:35:16Z","timestamp":1786707316201,"version":"build-2736575974"},"reference-count":5,"publisher":"Danish Medical Association","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Ugeskr L\u00e6ger"],"abstract":"<jats:p>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.<\/jats:p>","DOI":"10.61409\/v01260009","type":"journal-article","created":{"date-parts":[[2026,8,5]],"date-time":"2026-08-05T09:29:32Z","timestamp":1785922172000},"page":"1-3","source":"Crossref","is-referenced-by-count":0,"title":["Borrelia as a differential diagnosis to monoarthritis"],"prefix":"10.61409","author":[{"given":"Marie Louise","family":"Isaksen","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Steen","family":"B\u00e6rentzen","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Carsten Schade","family":"Larsen","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Victor N\u00e6stholt","family":"Dahl","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"40208","published-online":{"date-parts":[[2026,7,13]]},"reference":[{"key":"ref0","doi-asserted-by":"publisher","unstructured":"Stanek G, Fingerle V, Hunfeld KP et al. Lyme borreliosis: clinical case definitions for diagnosis and management in Europe. Clin Microbiol Infect. 2011;17(1):69-79. https:\/\/doi.org\/10.1111\/j.1469-0691.2010.03175.x","DOI":"10.1111\/j.1469-0691.2010.03175.x"},{"key":"ref1","doi-asserted-by":"publisher","unstructured":"Ornstein K, Broholm C, Dessau RB, Petersson AC. Lyme arthritis: demographic characteristics and Borrelia ospA genospecies in synovial fluid. A 17-year cohort study in Sweden. Ticks Tick Borne Dis. 2026;17(1):102582. https:\/\/doi.org\/10.1016\/j.ttbdis.2025.102582","DOI":"10.1016\/j.ttbdis.2025.102582"},{"key":"ref2","doi-asserted-by":"publisher","unstructured":"Arvikar SL, Steere AC. Lyme arthritis. Infect Dis Clin North Am. 2022;36(3):563-577. https:\/\/doi.org\/10.1016\/j.idc.2022.03.006","DOI":"10.1016\/j.idc.2022.03.006"},{"key":"ref3","unstructured":"M\u00fcller T, Locht H, Panum I et al. Lyme arthritis is rare in Eastern Denmark. Dan Med J. 2021;68(11):A05210423. https:\/\/ugeskriftet.dk\/dmj\/lyme-arthritis-rare-eastern-denmark"},{"key":"ref4","doi-asserted-by":"publisher","unstructured":"Unlu AM, Andersen NS, Larsen SL et al. Differentiating Lyme arthritis: a case-based review. Rheumatol Int. 2024;44(11):2671-2678. https:\/\/doi.org\/10.1007\/s00296-024-05618-0","DOI":"10.1007\/s00296-024-05618-0"}],"container-title":["Ugeskrift for L\u00e6ger"],"original-title":[],"deposited":{"date-parts":[[2026,8,14]],"date-time":"2026-08-14T11:05:01Z","timestamp":1786705501000},"score":1,"resource":{"primary":{"URL":"https:\/\/ugeskriftet.dk\/videnskab\/V01260009"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,13]]},"references-count":5,"URL":"https:\/\/doi.org\/10.61409\/v01260009","relation":{},"ISSN":["0041-5782","1603-6824"],"issn-type":[{"value":"0041-5782","type":"print"},{"value":"1603-6824","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,13]]}}}