Characteristics of persistent arthritis with refractory Kawasaki disease: a single-center retrospective study.

Arthritis is one complication of Kawasaki disease (KD); however, the clinical features of arthritis in KD have not been well clarified. We retrospectively investigated the characteristics of persistent arthritis beyond the subacute phase of KD. In this cohort, 49 of 243 patients (20%) developed arthritis, with 33 patients (14%) experiencing persistent arthritis.

Evaluation of the European League Against Rheumatism/American College of Rheumatology-2019 classification criteria in patients with childhood-onset systemic lupus erythematosus: a single-center retrospective study.

This study aimed to compare the sensitivity and specificity of the European League Against Rheumatism/American College of Rheumatology-2019 (EULAR/ACR-2019) classification criteria with prior classification schemes for patients with childhood-onset systemic lupus erythematosus (cSLE). This single-center retrospective study examined 53 patients with cSLE and 53 patients having antinuclear antibody (ANA) titers ≥ 1:80 but not cSLE as controls. Sensitivity and specificity were calculated for the EULAR/ACR-2019 criteria, original criteria reported earlier in 2019, the ACR-1997 criteria, and the Systemic Lupus International Collaborating Clinics-2012 (SLICC-2012) criteria.

Impaired Interleukin-18 Signaling in Natural Killer Cells From Patients With Systemic Juvenile Idiopathic Arthritis.

Objective: Systemic juvenile idiopathic arthritis (sJIA) is characterized by fever, arthritis, rash, hepatosplenomegaly, and macrophage activation syndrome; however, its pathogenesis is still unclear. Elevated serum interleukin (IL)-18 concentrations and decreased natural killer (NK) cell activity are characteristic of active disease; thus, we examined IL-18 signaling in NK cells from sJIA.

Methods: We analyzed mitogen-activated protein kinase (MAPK) p38 and nuclear factor κ light chain enhancer of activated B cells (NFκB) p65 phosphorylation in NK cells after in vitro recombinant IL-18 (rIL-18) stimulation in 31 patients with sJIA.

Clinical impact of myositis-specific autoantibodies on long-term prognosis of juvenile idiopathic inflammatory myopathies: multicentre study.

Objectives: This study aimed to investigate the clinical characteristics, treatment and prognosis of juvenile idiopathic inflammatory myopathies (JIIM) in Japan for each myositis-specific autoantibody (MSA) profile.

Methods: A multicentre, retrospective study was conducted using data of patients with JIIM at nine paediatric rheumatology centres in Japan. Patients with MSA profiles, determined by immunoprecipitation using stored serum from the active stage, were included.

External validation of the EULAR/ACR idiopathic inflammatory myopathies classification criteria with a Japanese paediatric cohort.

Objectives: To assess the performance of the EULAR/ACR idiopathic inflammatory myopathies (IIMs) classification criteria to classify juvenile IIMs (JIIMs) in an Asian paediatric population.

Methods: Sixty-eight JIIM patients and 49 non-JIIM patients diagnosed at seven major paediatric rheumatology centres in Japan between 2008 and 2015 were enrolled. Retrospective data were collected, and each patient's data form was submitted.

Clinical significance of subcutaneous fat and fascial involvement in juvenile dermatomyositis.

Subcutaneous involvement, including calcinosis and panniculitis, is a more common complication in juvenile dermatomyositis (JDM) than in adult dermatomyositis. Magnetic resonance imaging (MRI) is useful for evaluating disease distribution. We investigated the clinical significance of subcutaneous involvement in JDM.

Primary varicella infection in children with systemic juvenile idiopathic arthritis under tocilizumab therapy.

We report the clinical course and outcome of primary varicella infection in six children with systemic juvenile idiopathic arthritis (sJIA) receiving tocilizumab. None had disseminated or fatal varicella infection, but one patient developed macrophage activation syndrome (MAS) and another had an arthritis relapse. All patients had a significant elevation of serum IL-6 levels, and the two children who developed MAS or arthritis relapse showed high serum IL-18 levels, which could cause a sJIA flare-up.