To compare the clinical and laboratory findings of multisystem inflammatory syndrome in children (MIS-C), patients with Kawasaki disease (KD) and with macrophage activating syndrome due to systemic juvenile idiopathic arthritis (sJIA-MAS) on real-life data. Patients diagnosed with MIS-C, KD, and sJIA-MAS from 12 different centers in Turkey who were followed for at least 6 months were included in the study. Demographic, clinical, and laboratory findings of all patients were analyzed. A total of 154 MIS-C, 59 KD, and 31 sJIA-MAS patients were included. The median age of patients with MIS-C were higher than those with KD while lower than those with sJIA-MAS (8.2, 3, 12 years, respectively). Myalgia (39.6%), cardiac (50.6%), gastrointestinal (72.7%), and neurological (22.1%) involvements were more common in patients with MIS-C compared to others. MIS-C patients had lower levels of lymphocyte (950 vs 1700 cells/µl) and thrombocyte (173,000 vs 355,000 cells/µl) counts and higher pro-BNP (1108 vs 55 pg/ml) levels than KD. Ferritin levels were higher in patients with MIS-C compared to patients with KD while they were lower than patients with sJIA-MAS (440, 170, 10,442 ng/ml, respectively). Patients with MIS-C had a shorter duration of hospitalization than sJIA-MAS ( p = 0.02) while they required intensive care unit admission more frequently (55 vs 8 patients, p < 0.001). The median MAS/sJIA score of MIS-C patients was − 1.64 (− 5.23 to 9.68) and the median MAS/sJIA score of sJIA-MAS patients was −2.81 ([− 3.79] to [− 1.27]). MIS-C patients displayed certain differences in clinical and laboratory features when compared to KD and sJIA-MAS. Definition of the differences and similarities between MIS-C and the other intense inflammatory syndromes of childhood such as KD and MAS will help the clinicians while making timely diagnosis.

The aim of the research was to further extend current knowledge of whether severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) disease 2019 (COVID-19) entails a risk for children with various rheumatic diseases under immunosuppressive treatment. Telephone survey was administered by conducting interviews with the parents from May 1, 2020 to May 20, 2020. A message containing a link to the actual questionnaire was sent to their phones simultaneously. The medical records of the patients were reviewed for gathering information about demographic data, clinical follow-up, and treatments. Patients who were followed-up under immunosuppressive treatment (n = 439) were attempted to be contacted. The diagnostic distribution of patients (n = 414) eligible for the study was as follows: juvenile idiopathic arthritis (JIA) (n = 243, 58.7%), autoinflammatory diseases (n = 109, 26.3%), connective tissue diseases (n = 51, 12.3%), and vasculitis (n = 11, 2.7%). In the entire cohort, the mean age was 12 ± 4.7 years, and 54.1% (n = 224) were female. Nine patients have attended the hospital for COVID-19 evaluation, 6 of whom were in close contact with confirmed cases. One patient with seronegative polyarticular JIA, previously prescribed methotrexate and receiving leflunomide during pandemic was identified to be diagnosed with COVID-19. None, including the confirmed case, had any severe symptoms. More than half of the patients with household exposure did not require hospitalization as they were asymptomatic. Although circumstances such as compliance in social distancing policy, transmission patterns, attitude following contact may have influenced the results, immunosuppressive treatment does not seem to pose an additional risk in terms of COVID-19.

Familial Mediterranean fever (FMF) is the most common monogenic autoinflammatory disease manifesting phenotypic heterogeneity. It is a clinically diagnosed disease supported by MEditerranean FeVer (MEFV) gene mutation analysis. However, the phenotype-genotype correlation is not yet established clearly. We aimed to determine the clinical findings, phenotype-genotype correlation, and treatment outcomes within a large pediatric FMF cohort. The medical charts of children with FMF who were diagnosed and followed up at the eight pediatric rheumatology units were reviewed retrospectively. All patients in the cohort were analyzed for sequence variants in exon 2,3,5 and 10 of the MEFV gene. Patients without any mutations or with polymorphisms including R202Q were excluded. A total of 3,454 children were involved in the study. The mean ± standard deviation of current age, age at symptom onset, and age at diagnosis were 12.1 ± 5.2, 5.1 ± 3.8, and 7.3 ± 4.0 years, respectively. Of 3,454 patients, 88.2% had abdominal pain, 86.7% had fever, 27.7% had arthritis, 20.2% had chest pain, 23% had myalgia, and 13.1% had erysipelas-like erythema. The most common MEFV mutation patterns were homozygous (32.5%) and heterozygous (29.9%) mutations of exon 10. Homozygous M694V was present in 969 patients (28.1%). Allele frequencies of common mutations were M694V (55.3%), M680I (11.3%), V726A (7.6%), and E148Q (7.2%). Children carrying homozygous or compound heterozygous exon 10 mutations had an earlier age of disease onset (4.6 vs. 5.6 years, p = 0.000) and a higher number of attacks per year (11.1 vs. 9.6, p = 0.001). Although 8% of the patients had a family history of amyloidosis, 0.3% (n = 11) had the presence of amyloidosis. M694V homozygosity was detected in nine patients who developed amyloidosis. Colchicine resistance was present in 4.2% of our patients. In this largest pediatric cohort reviewed and presented to date, patients with exon 10 mutations, particularly the M694V homozygous mutation, have been demonstrated earlier disease onset, annual attack count, and more frequent colchicine-resistant cases. Although E148Q is considered as a polymorphism in some populations, it was identified as a disease-causing mutation in our cohort. Secondary amyloidosis is still happening in adults however, it is extremely rare among children, presumably due to increased awareness, tight control, and the availability of anti-IL1 agents in colchicine-resistant cases.

No abstract