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Reactive arthritis after COVID-19 Bo Langhoff Hønge ‍ ‍, 1,2 Marie-Louise From Hermansen, 1,3 Merete Storgaard 3 Case report

1 Department of Internal Medicine, Randers Regional Hospital, Denmark, Randers, Denmark 2 Department of Infectious Diseases, Aarhus University Hospita, Randers, Denmark 3 Department of Rheumatology, Aarhus University Hospital, Aarhus, Denmark

of respiratory distress at the first admission related to COVID-19, he had consistently felt some short- ness of breath and tiredness, and these symptoms still prevailed. There were no other symptomatic complaints or objective findings. Body temperature was 37.7 ℃ measured rectally. Blood pressure was 144/92 mm Hg, heart rate 92 beats per minute, respiratory rate 18/minute and peripheral satura- tion 93%–95%. The patient was slightly overweight (body mass index=26.5 kg/m 2 ) but had no previous or concom- itant illnesses, and he did not take any medications prior to admission. He informed that his mother had general osteoarthritis and gout. There were no predispositions to autoimmune diseases. INVESTIGATIONS At the first admission, a throat swab was positive for SARS-CoV-2 RNA by PCR. At the second admis- sion, the throat swab was negative, but a tracheal secretion test turned out positive. Thus, the patient was kept in isolation during both hospitalisations. During both admissions, the patient had elevated acute-phase reactants. CRP peaked at 279 mg/L and 327 mg/L at the first and the second admission, respectively (figure 2). Total leucocyte count was normal during first admission although the number of lymphocytes was decreased to 0.66×10 9 cells/L (normal range: 1.30–3.50×10 9 cells/L). However, lymphocytes normalised after 5 days of hospital- isation. During the second admission, the total leucocyte count was elevated to 13.6×10 9 cells/L (normal range: 3.50–10×10 9 cells/L) with elevated neutrophils. At the second admission, X-ray examination of all major joints was made. There was a profound accumulation of fluid in the right knee and the right-side talocrural joint. There were no signs of arthritis. Synovial fluid was aspirated from the right knee. Unfortunately, the sample for cell count was misplaced. By light microscopy, a large proportion

SUMMARY A previously healthy 53-year-old man was hospitalised for 12 days due to COVID-19 with shortness of breath. A few days after discharge from hospital, the patient developed fever and severe pain in several joints in the lower extremities. The pain was so severe that the patient was unable to stand on his feet. Synovial fluid from the right-side knee contained a high number of polynuclear cells and a few mononuclear cells. Microscopy, culture and PCR tests for bacterial infection were all negative. Furthermore, the patient tested negative for rheumatoid factor, anti-cyclic citrullinated peptide and human leukocyte antigen (HLA)-B27. Thus, the condition was compatible with reactive arthritis. The condition improved markedly after a few days’ treatment with non-steroid anti-inflammatory drugs and prednisolone. BACKGROUND The rapid global spread of SARS-CoV-2 constitutes a major human threat. COVID-19, the disease caused by SARS-CoV-2, usually manifests as pneumonia with hypoxia. In severe cases, the virus activates the immune system leading to systemic inflammation and immune dysregulation. Complications include kidney failure, myocardial dysfunction, throm- botic events and gastrointestinal symptoms. 1 Due to the novelty of the disease, the picture of post- COVID-19 sequelae is still unclear. We here report a case of reactive arthritis after COVID-19. CASE PRESENTATION A 53-year-old man developed fatigue, shortness of breath and fever up to 40°C 2 days after attending a seminar at work. He took a throat swab test for SARS-CoV-2 infection, and the test result was positive. Due to persistent fever and increasing pulmonary symptoms, he was admitted at Randers Regional Hospital. At admission, there was hypoxia <90% despite oxygen supply, and the patient was transferred to the intensive care unit at Aarhus University Hospital. For the next 12 days, he grad- ually improved without the need for mechanical ventilation. At discharge, the patient was stable and had no fever, and C reactive protein (CRP) levels were normal. Four days later, the patient presented again at Randers Regional Hospital with severe pain in several joints in the lower extremities. The pain begun shortly after he was discharged and affected the right knee, both ankles and the lateral side of the left foot. This prevented the patient from walking, and he was barely able to stand on his feet. Correspondingly, at examination, the right knee and the ankles were found swollen, warm, tender and slightly reddish (figure 1A,B). Since the debut

Correspondence to Dr Bo Langhoff Hønge; b ohonge@gmail.c om

Accepted 16 February 2021

To cite: Hønge BL, Hermansen M-LF,

Storgaard M. BMJ Case Rep 2021; 14 :e241375. doi:10.1136/bcr-2020- 241375

Figure 1 (A,B) The right knee was markedly swollen.

Hønge BL, et al . BMJ Case Rep 2021; 14 :e241375. doi:10.1136/bcr-2020-241375