An Unforeseen Outcome of COVID-19: The Triggering of Adult-Onset Still's Disease.

Background: Adult-onset Still's disease (AOSD) is a rare auto-inflammatory disorder with unknown etiology by which an infectious trigger is usually responsible for the onset of the disease. It is diagnosed by exclusion when certain clinical, biochemical, and radiological criteria are met after excluding all other potential causes. Besides, SARS‑CoV‑2 infection is increasingly being reported to have autoimmune complications. In the literature, 3 AOSD cases have been reported to be triggered by SARS‑CoV‑2 infection and here we report the fourth. Case presentation: A 24-year-old female doctor suffered from fever, sore throat, and mild cough a few days after a shift in the COVID-19 ward. A week later, she developed polyarthritis, salmon-colored rash, and high-grade fever, and the laboratory findings were indicating an inflammatory syndrome. COVID-19 IgM antibodies were positive indicating recent infection. After running a battery of tests, infectious, neoplastic, and rheumatic causes of these symptoms that persisted for about 50 days were excluded which led to a diagnosis of AOSD after fulfilling its criteria with subsequent treatment with methylprednisolone. Drastic improvement was achieved with no recurrence until the date of reporting. Conclusion: This case presents a new consequence of COVID-19 and adds to the emerging cumulative experiences with this disease. We encourage health care professionals to report such cases to further understand the nature of this infection and its possible outcomes.