Adult-onset Still's disease

ASD is as a rare, polygenetic, autoinflammatory disorder. According to EULAR/PReS guidelines, systemic JIA and ASD are considered the same condition and designated as Still's disease.

The exact pathophysiology of ASD is unknown, but it is characterized by overactive immune responses and excessive production of pro-inflammatory cytokines, such as TNF-α, IL-1, IL-6, IL-8, and IL-18.

The incidence of ASD worldwide is estimated at 0.16-0.4 per 100,000 person-years.

Risk factors for developing ASD are not fully understood due to the rarity of the condition, but several HLA associations have been identified, suggesting a genetic predisposition.

ASD presents with a variety of symptoms and course, including monocyclic, polycyclic, and chronic patterns. Common symptoms include fever, rash, arthralgia, arthritis, throat pain, lymphadenopathy, and myalgia. Less common presentations include pleuritis, pericarditis, and abdominal pain. The most commonly involved regions are the knees, ankles, and wrists, followed by elbows, shoulders, and fingers. Polyarticular course is more often than oligo- or monoarticular involvement. Elevation of inflammatory markers, including ESR, CRP, and serum ferritin levels, is very common. Systemic complications include macrophage activation syndrome and lung involvement (such as pneumonitis, ILD, diffuse alveolar hemorrhage), which are associated with an unfavorable prognosis.

The prognosis of ASD is variable and can be influenced by several factors. Elevated ESR and refractoriness to corticosteroids have been associated with poor prognosis.