Association between adult-onset still's disease and COVID-19: A report of two cases and brief review.

Adult-onset still's disease is a rare multisystemic autoinflammatory disorder with an estimated annual incidence of 0.16-0.62 per 100,000 individuals worldwide. It is typically considered a diagnosis of exclusion. SARS-CoV-2 is a positive-strand RNA virus that causes the acute respiratory infection known as COVID-19. Although COVID-19 predominantly affects the respiratory system, it has also been proposed as a trigger for autoimmune diseases, like adult-onset still's disease, as both share considerable pathophysiological similarities. We report two cases of patients with adult-onset still's disease, where COVID-19 was the most likely cause for a flare-up in the first case and the most likely trigger for adult-onset still's disease in the second case. Although the exact mechanism is not entirely understood, the similarities between adult-onset still's disease and COVID-19 could indicate a shared underlying mechanism explaining why COVID-19 can lead to adult-onset still's disease or worsen its symptoms. Further research is necessary to fully comprehend the intricate connections between the two conditions and their immunological effects.