COVID-19 in a patient with new adult-onset Still disease: A case report

Adult-onset Still disease (AOSD) is a systemic autoinflammatory illness of unknown cause. Its manifestations comprise fever; arthritis or arthralgia; and skin rash with high inflammatory markers and ferritin levels. Coronavirus disease 2019 (COVID-19) shares several clinical features and laboratory markers of AOSD: making it challenging to differentiate between the 2 conditions.

A 29-year-old woman presented with fever, skin rash, and polyarthritis 4 weeks before admission. Two weeks after illness onset, she had an infection with symptoms similar to those of COVID-19. She observed that her symptoms worsened, and new symptoms appeared including headache; vomiting; diarrhea; and loss of taste and smell. The patient tested positive for severe acute respiratory syndrome coronavirus 2 using polymerase chain reaction.

The patient was diagnosed with AOSD complicated with COVID-19 after exclusion of other possible causes of her illness, such as infections, malignancy, or underlying rheumatological disease.

The patient was administered corticosteroids and methotrexate. The patient responded quickly, particularly to corticosteroids.

This is the second reported case of COVID-19 in a patient with AOSD. She experienced COVID-19 shortly after having AOSD, indicating that those with AOSD might have a higher risk of COVID-19 infection. Furthermore, she developed the most prevalent COVID-19 symptoms. However, distinguishing most of these symptoms from AOSD manifestations was difficult.

Early diagnosis and differentiation between AOSD and COVID-19 and prompt initiation of treatment are required.