Abstract
Currently, there are no specific diagnostic investigations for systemic juvenile idiopathic arthritis
（s-JIA）. Various investigations are considered when making a differential diagnosis. During the 5th
Pediatric Rheumatology Workshop held in 2017, we interviewed 17 Japanese pediatric rheumatology experts
about the investigations they conduct in the initial diagnostic process for s-JIA. Bone marrow aspiration was
preferred by 82％ of experts. Routine use of joint magnetic resonance imaging and measurement of serum
IL-18 for an initial diagnostic approach appeared to be controversial. Fluorodeoxyglucose-positron emission
tomography or Gallium scintigraphy were not frequently conducted. Although each investigation was known
to play a certain role in the diagnosis of s-JIA, they were often not conducted for reasons such as radiation
exposure, invasiveness, availability of the investigation in that hospital, and health insurance coverage. In
addition, investigations necessary for diagnosis should be selected on an individual basis because patients
with s-JIA show diverse initial manifestations. There was consensus among the experts that exclusion of
malignancy is important when diagnosing s-JIA； therefore, selected investigations should be performed
carefully.
