🔥 Adult-Onset Still's Disease (AOSD) is a rare systemic autoinflammatory disorder. It classically presents with high spiking fevers, arthralgia/arthritis, and a distinctive salmon-pink rash. Often mimics viral infection → consider in PUO cases with negative autoantibodies.

ℹ️ About

Typically affects young adults (16–35 yrs).
Often begins as pyrexia of unknown origin (PUO).
Suspected viral trigger in some cases.

👩‍⚕️ Clinical Features

Daily spiking fevers up to 40°C 🌡️ with sweats & chills.
Severe sore throat (common early feature).
Rash: salmon-pink, evanescent, maculopapular (often on trunk & proximal limbs, worse with fever spikes).
Weight loss, malaise, hepatosplenomegaly, lymphadenopathy.
Arthralgia → chronic destructive arthritis in late disease.

🔬 Investigations

RF and ANA negative (helps exclude RA & lupus).
↑ ESR, ↑ CRP.
Leukocytosis (WCC often >40,000) with neutrophilia.
Thrombocytosis.
Ferritin markedly raised (>3000 ng/mL is highly suggestive).

Salmon-coloured rash in Still's disease

⚠️ Complication: Macrophage Activation Syndrome (MAS)

Life-threatening “cytokine storm” syndrome with pancytopenia, DIC, liver failure.
Triggered by excessive immune activation.
Treatment: High-dose corticosteroids ± immunosuppressants (e.g. ciclosporin, biologics).

💊 Management

🟢 Mild disease: NSAIDs (e.g. aspirin 1 g TDS, ibuprofen).
🟠 Moderate/severe: Corticosteroids (e.g. prednisolone 40–60 mg/day).
⚙️ Disease-modifying therapy: Methotrexate for steroid-sparing effect.
🧬 Biologics:
- TNF inhibitors (etanercept, infliximab).
- IL-1 inhibitors (anakinra, canakinumab).
- IL-6 inhibitors (tocilizumab).

Cases — Adult-Onset Still’s Disease (AOSD)

Case 1 — Classic triad 🔥: A 28-year-old woman presents with daily spiking fevers for 2 weeks, evanescent salmon-pink macular rash on trunk/arms, and polyarthritis affecting wrists and knees. Bloods: markedly raised ferritin (>5000 µg/L), neutrophilia, raised CRP/ESR. ANA and RF negative. Diagnosis: classic AOSD. Managed with NSAIDs and corticosteroids.
Case 2 — Systemic features 🫁: A 35-year-old man presents with fever, sore throat, lymphadenopathy, hepatosplenomegaly, and pleuritic chest pain. Labs: ferritin 10,000 µg/L, abnormal LFTs, leukocytosis. Excluded infection and lymphoma. Diagnosis: systemic AOSD with serositis. Treated with steroids; later escalated to methotrexate for steroid-sparing effect.
Case 3 — Severe complication 🫀: A 41-year-old woman with known AOSD is admitted with shock, fever, cytopenias, coagulopathy, and high ferritin. Diagnosed with macrophage activation syndrome (MAS), a life-threatening complication of Still’s disease. Managed in ITU with IV methylprednisolone and ciclosporin, with haematology input.

Teaching Point 🩺: Adult-onset Still’s disease is an autoinflammatory disorder characterised by quotidian fevers, evanescent rash, and arthritis. Ferritin is often massively elevated. Always rule out infection, malignancy, and autoimmune mimics. MAS/HLH is a feared complication.

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Adult Onset Stills Disease