Overview
Adult-onset Still’s disease (AOSD) is an inflammatory disorder characterised by fever, joint pain, and a salmon-pink maculopapular rash. It is a form of Still’s disease (also known as systemic juvenile idiopathic arthritis).
Epidemiology
- AOSD is rare and affects up to 0.4 per 100,000 people in Europe
- It has a bimodal age distribution with two peaks at 15-25 years and 36-46 years
Presentation
The main features are:
- Joint pain
- Fever – usually worsens in the late afternoon/early evening with a worsening of joint pain and rashes
- Rash – a transient, salmon-pink, maculopapular rash
Other features may include:
- Lymphadenopathy
- Pleurisy
- Pericarditis
- Hepatomegaly
- Abdominal pain
Investigations
Overview
The diagnosis of AOSD is based on clinical criteria, however, some tests may be considered to rule out other causes such as:
- Full blood count (FBC):
- May show leukocytosis, predominantly neutrophils
- May show normocytic, normochromic anaemia
- May show thrombocytosis
- Ferritin:
- Elevated to around 5x the upper limit of normal in most patients with AOSD (relatively high sensitivity ~80%)
- Rheumatoid factor (RF) and anti-nuclear antibodies (ANA):
- Negative in most patients
- C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR):
- Often elevated
- X-ray/MRI:
- May be normal or show slight joint space narrowing and periarticular osteopenia
Management
Overview
NSAIDs are given first for symptom relief. Steroids are also added, however, they carry side effects including Cushing’s syndrome and stunted growth in younger people. If symptoms persist, methotrexate or anti-TNF therapy may be considered.
