Adult-onset Still's disease following COVID-19: a case report and literature review.

A 59-year-old man developed adult-onset Still's disease 11 days after contracting COVID-19. He presented with high fever, polyarthritis, erythema, sore throat, and high levels of C-reactive protein and ferritin; treatment with glucocorticoids and methotrexate led to disease remission. We reviewed the clinical characteristics of 12 cases (11 from the literature and the present case) of adult-onset Still's disease following COVID-19. Eight cases involved females, with a median age of 54 years (19-59 years), and the median time from COVID-19 to Still's disease onset was 12.5 days. Frequencies of high fever, arthralgia, typical skin lesion, sore throat, liver damage, and increased neutrophil count did not differ from cases of non-COVID-related adult-onset Still's disease. Serum ferritin levels were increased in all cases (median 6354 ng/ml). Complications were infrequent, with macrophage activation syndrome reported in one case. Immunosuppressive drugs and biologic agents were used in five and three cases, respectively, and all cases had good outcomes. Our review suggests that adult-onset Still's disease develops early after COVID-19, presenting with clinical findings similar to non-COVID-19-related cases, and has few severe complications and a good prognosis.