This is Systemic Onset JIA.
- The diagnosis is by exclusion - infection, malignancy to be considered.
- The presentation of SOJIA can be indolent or acute. The arthritis may not be apparent at first but may follow 4-6 weeks after the onset of systemic symptoms.
- Bone marrow may need to be considered to exclude malignancy (leukaemia or neuroblastoma). The peripheral blood film may not show blasts with acute leukaemia.
- It is important to exclude malignancy (leukaemia) before starting corticosteroids as the survival from leukaemia is much worse. It is important to consider a bone marrow if there are atypical features such as a low or normal platelet count (platelets are usually very high with SOJIA), a differential count marrow may need to be considered to exclude malignancy (leukaemia or neuroblastoma). The peripheral blood film may not show blasts with acute leukaemia or where the serum ferritin, is normal or only mildy raised (ferritin, as an acute phase reactant is usually very high in active SOJIA [usually >1000ng/L]).
- In this case the child was unwell, the ferritin was high and there was no apparent arthritis.
Repeat blood tests showed persistently raised acute phase reactants. She was treated with IV corticosteroids, daily over 3 days, improved rapidly and discharged home on oral steroids to be reviewed after one week. She returned with more joint pain, recurrence of rash and fever. She had polyarthritis.
She was given further course of IV corticosteroids over 3 days and started on subcutaneous methotrexate weekly and discharged on oral steroids to be reviewed for blood tests in 4 weeks.
The family attended weekly to meet the nurse specialist and taught how to administer methotrexate at home. At her 4 week review she was well but had ongoing arthritis, intermittent rash but no fever. She was intolerant of methotrexate, even with antiemetics. After discussion with her family she was started on tocilizumab (IV infusion on the day unit) every fortnight and was able to continue lower dose of subcutaneous methotrexate. After 3 months she was well, in remission and had stopped her steroids. She attends the day unit for infusions of tocllizumab.
The photograph shows the typical rash of systemic JIA - this often appears at time of fever and can be easily missed!
The chart shows the typical fever chart - spikes in the evening but normal in between.