Adult-Onset Still’s Disease Misdiagnosed as Acute Fibrinous and Organizing Pneumonia: A Case Report and Literature Review

Adult-onset Still’s disease (AOSD) is a rare condition that lies between autoinflammatory syndrome and autoimmune disease. The main clinical manifestations include fever, chills, rash, joint swelling and pain, peripheral blood leukocytosis, splenomegaly, etc. It is a systemic disease affecting between 1 and 34 people per million. The average age of onset is 35 years old, with a slightly higher prevalence rate in women. Since AOSD lacks early specific symptoms and signs, non-specialist doctors have limited understanding of the disease, and patients are prone to clinical misdiagnosis, mistreatment, and delayed disease progression. This paper reports a patient whose AOSD was misdiagnosed as acute fibrinous and organizing pneumonia.