Adult-onset Still's disease (AOSD)

Adult-onset Still's disease is a rare systemic inflammatory condition, considered part of the autoinflammatory and autoimmune spectrum, that produces spiking fevers, an evanescent salmon-colored rash, and joint inflammation, often alongside an elevated white blood cell count. Current understanding describes its pathogenesis as involving genetic background and infectious triggers that activate macrophages and neutrophils, with cytokines including interleukin-1, interleukin-6, interleukin-18, and TNF-alpha driving the inflammatory episodes.

Because it is uncommon, solid prevalence figures are limited and estimates vary between reports, so a precise figure is not given here. The disease can follow a single self-limited episode, a relapsing pattern, or a persistent joint-centered course, and macrophage activation syndrome, a severe complication, is reported in up to 15 percent of cases.

Common signs

Spiking daily fevers, a salmon-colored rash that often comes and goes with the fever, joint and muscle pain, and sore throat. Fatigue and a general unwell feeling are common during flares, and some people develop ongoing arthritis.

This is a plain-language summary for orientation, not a diagnosis. Mechanisms are described as current understanding, not settled fact. Work with your own clinician for your care.