2022 Volume 34 Issue 2 Pages 137-143
The patient was a 22-year-old man with a history of persistent fever since August 20XX, and subsequent polyarthritis. The patient consulted a local physician who prescribed antibiotics, which did not improve his symptoms. He was referred to our department 12 days after his fever started. Blood test revealed a mildly low white blood cell count of 3,300/μL. Rheumatoid factors, anti-cyclic citrullinated peptide antibodies, and antinuclear antibodies were not elevated. Epstein Barr Virus antibody test revealed that the patient was previously infected, he tested negative for human immunodeficiency virus antibodies, parvovirus B19 antibodies, and cytomegalovirus C7-HRP. Physiological findings included bilateral ankle joint inflammation. Synovial fluid collected from his right ankle joint revealed a cell count of 25,300/μL, which is in accordance with inflammatory synovial fluid. Histiocytes comprised 88% of the cells. Enlarged lymph nodes were also found in the right axilla. He was diagnosed with Kikuchi-Fujimoto disease（KFD）based on lymph node biopsy of the same site. There are previous studies of KFD complicated with joint inflammation; however, synovial fluid findings have not been reported. Histiocyte-dominant synovial fluid is consistent with one of the disease conditions of KFD. Arthrocentesis is easy to perform and may provide knowledge on the characteristics of synovial fluid that help in diagnosing KFD. Future studies should include more cases of KFD with arthritis.
