Investigations for adult-onset Still disease

The most common laboratory findings in adult-onset Still disease are listed in Clinical features and investigation findings in adult-onset Still disease. There are no pathognomonic laboratory findings for the diagnosis of adult-onset Still disease, although sometimes biopsies of affected tissues (eg skin, bone marrow) are performed to support a diagnosis or a suspicion of macrophage activating syndrome (MAS).

Adult-onset Still disease is not associated with autoantibodies and the diagnosis is supported by the absence of both antinuclear antibodies (ANA) and rheumatoid factor (RF).