Juvenile arthritis systemic type, (Stills disease in children) (ICD-10 M08.2)
Systemic childhood arthritis / systemic JIA is characterized by high fever peak without infection. Varying light-red rashes that follow fever peaks and joint inflammation are common. The disease has common features with the periodic fever syndrome (autoinflammatory diseases), but is considered as childhood arthritis.
This form of childhood arthritis represents 10% of all JIA and occurs as common among girls as boys, mostly among young children, but all age groups can be attacked. There is also an adult form (Adult Stills disease)
The most common disease onset is 2 - 4 years of age.
Daily fever peaks over at least 2 weeks (without effect of any antibiotic cures)
- The children are often very exhausted during the fever attacks
- Normal body temperature between spiking episodes
- A pink ("salmon-red") rash can follow the fever peaks
- Enlarged (swollen) lymph nodes, large liver and spleen occur
- Arthritis (joint inflammation) in one or more joints (knees, wrists, ankles, fingers, neck or hips) is common in the course of the disease
- Some children get inflammation in pericardium (pericarditis), the lung (pleuritis) or Abdominal peritoneum (peritonitis) without bacteria or other infection present
- Treatment with IL-6 inhibitor (tocilizumab) or IL inhibitor (anakinra, canakinumab) has in some cases led to hypersensitivity reaction (hypersensitivity) with new rash, lung manifestation, eosinophilia, lymphopenia and high blood ferritin (reference: Saper VJ, 2019)
- High inflammatory tests (CRP and ESR)
- High levels of white blood cells and platelets.
- High ferritin without the child having too much iron in the body
Macrophage Activation Syndrome (MAS)
Seriously affected children may have a similar picture of illness BUT (persistent high fever, large liver and spleen, swollen lymph nodes, affected brain function, changes in blood tests). Typical differences in blood tests that MAS causes:
- Higher Liver Enzymes (ALAT, ASAT, LD), most often over 2-3 x upper reference ranges
- Higher Triglycerides
- Higher Ferritin (most often> 1500)
- Lower immersion reaction (SR), but often moderate over the reference range
- Ferritin / SR ratio of at least 21,5 has shown 82% sensitivity and 78% specificity for MAS in systemic JIA compared to systemic JIA without MAS (reference: Eloseily EMA, 2019)
- Number of white blood cells slightly elevated (4,6-16,3). Systemic JIA usually results in significantly elevated values (12-22)
- Reference: Minola F, 2019
- Rarely is there sufficient effect of NSAIDs (for example ibuprofen or naproxen)
- Generally, there is a need for more effective, disease-modulating drugs.
- Healing treatment is not available, but in many cases the disease stops by itself, but after a very varied period of time (disease duration from weeks to many years)