Differentiating Multisystem Inflammatory Syndrome in Children from Kawasaki Disease During the Pandemic.

OBJECTIVE: We aimed to delineate the distinctive characteristics that aid in distinguishing between Kawasaki disease (KD) and multisystem inflammatory syndrome in children (MIS-C) with KD-like manifestations during the pandemic. MATERIALS AND METHODS: We evaluated KD patients and MIS-C patients with KD-like symptoms admitted during the pandemic (between January 2021 and December 2022). RESULTS: Thirty-three MIS-C patients and 15 KD patients were included. Kawasaki disease patients were younger than MIS-C patients (3.4 vs. 7.6 years). Rash (P = .044, 100% vs. 75.7%), oral mucosal changes (P = .044, 100% vs. 75.7%), and cervical lymphadenopathy (P = .001, 93.3% vs. 42.4%) were more common in KD. Multisystem inflammatory syndrome in children: patients had more hypotension (P = .002, 45.4% vs. 0), gastrointestinal (P .001, 72.7% vs. 13.3%), and respiratory symptoms (P = .044, 24.2% vs. 0). Multisystem inflammatory syndrome in children patients also had low lymphocyte and thrombocyte counts and elevated levels of d-dimer, ferritin, and cardiac parameters, unlike KD patients. Multisystem inflammatory syndrome in children patients exhibited a notable reduction in left ventricular systolic function in echocardiography. Another significant difference with regard to management was the anakinra treatment, which was prescribed for MIS-C patients. CONCLUSION: Although MIS-C patients might display a clinical resemblance to KD, several features could help differentiate between MIS-C and classical KD. Specific clinical (hypotension, gastrointestinal, and respiratory symptoms) and laboratory (low lymphocyte and thrombocyte counts with higher C-reactive protein, ferritin, d-dimer, and cardiac parameters) features are characteristic of MIS-C. In addition, divergence in management strategies is evident between the 2 diseases, as biologic drugs were more prevalently employed in MIS-C patients than in classical KD patients.

Is it possible to predict a disease course prone to macrophage activation syndrome at systemic juvenile idiopathic arthritis diagnosis?

OBJECTIVES: Macrophage activation syndrome (MAS) is a severe complication of systemic juvenile idiopathic arthritis (SJIA). We aimed to compare the characteristics of SJIA patients who developed MAS in the disease course to those who never experienced MAS. METHODS: Patients with SJIA were included. The features of the patients at the time of SJIA diagnosis were compared. Multivariate logistic regression and ROC analyses were used while evaluating factors associated with MAS. RESULTS: Overall, 126 SJIA patients (M/F:1.17) were included. Eighty-six (68.2%) never had MAS. At the time of SJIA diagnosis, age was younger; the duration of fever was longer; rash, hepatomegaly, and splenomegaly were more frequent and arthralgia/arthritis was less common among patients who had MAS in the follow-up than those who never had MAS. Also, white blood cell, neutrophil, and platelet counts and fibrinogen were lower, while transaminases, lactate dehydrogenase, triglyceride (TG), and ferritin levels were higher among patients with MAS than those without MAS. The multivariate regression analysis disclosed age at symptom onset, duration of fever, platelet count, TG and ferritin levels as independent MAS predictors. For ferritin level/platelet count (F/P) ratio at the time of SJIA diagnosis, a threshold of ≥1.1 performed best to predict a MAS-prone disease course with a sensitivity of 90% and a specificity of 82.6%. CONCLUSION: The F/P ratio at the time of SJIA diagnosis may be a promising biomarker to predict MAS-prone disease course in SJIA. Determining MAS-prone patients at the time of SJIA diagnosis could assist physicians while tailoring SJIA treatment individually. Key points • Systemic juvenile idiopathic arthritis (SJIA) patients with macrophage activation syndrome (MAS) differ from SJIA patients who never have MAS, at the time of SJIA diagnosis. • It could be possible to predict a MAS-prone disease course at the time of SJIA diagnosis. • The ferritin/platelet ratio is a promising biomarker for predicting MAS-prone SJIA disease course.

Subclinical enthesitis in enthesitis-related arthritis and sacroiliitis associated with familial Mediterranean fever.

OBJECTIVES: In our study, we investigated the presence of subclinical enthesitis by ultrasonography (US) in asymptomatic patients with enthesitis-related arthritis (ERA) and sacroiliitis associated with familial Mediterranean fever (FMF). METHODS: A total of 50 patients, including 35 patients with ERA and 15 with sacroiliitis associated with FMF, were included in the study. All patients were evaluated with US by a paediatric radiologist. Enthesis of seven tendons (common extensor and flexor tendons, quadriceps tendon, proximal and distal patellar tendon, Achilles tendon, and plantar fascia) was examined on both sides. RESULTS: Subclinical enthesitis was detected in 10 ERA (28.5%) and three FMF (20%) patients. Enthesitis was radiologically diagnosed in 16 (2.3%) out of 700 evaluated entheseal sites. The most frequent sites of enthesitis were Achilles (37.5%) and quadriceps (31.3%) tendons. All patients were in clinical remission and had no active complaints, and acute phase reactants were within normal limits. Therefore, the patients were followed up without treatment change. However, disease flare-up was observed in three of these patients (23.1%) during the follow-up, and their treatments were intensified. CONCLUSIONS: Our results showed that the US can be particularly helpful in detecting subclinical enthesitis and predicting disease flare-ups.

A score for predicting colchicine resistance at the time of diagnosis in familial Mediterranean fever: data from the TURPAID registry.

OBJECTIVES: Colchicine forms the mainstay of treatment in FMF. Approximately 5-10% of FMF patients are colchicine resistant and require anti-IL-1 drugs. We aimed to compare the characteristics of colchicine-resistant and colchicine-responsive patients and to develop a score for predicting colchicine resistance at the time of FMF diagnosis. METHODS: FMF patients (0-18 years) enrolled in the Turkish Paediatric Autoinflammatory Diseases (TURPAID) registry were included. The predictive score for colchicine resistance was developed by using univariate/multivariate regression and receiver operating characteristics analyses. RESULTS: A total of 3445 FMF patients [256 (7.4%) colchicine-resistant and 3189 colchicine-responsive) were included (female:male ratio 1.02; median age at diagnosis 67.4 months). Colchicine-resistant patients had longer, more frequent attacks and were younger at symptom onset and diagnosis (P < 0.05). Fever, erysipelas-like erythema, arthralgia, arthritis, myalgia, abdominal pain, diarrhoea, chest pain, comorbidities, parental consanguinity and homozygosity/compound heterozygosity for exon 10 MEFV mutations were significantly more prevalent among colchicine-resistant than colchicine-responsive patients (P < 0.05). Multivariate logistic regression analysis in the training cohort (n = 2684) showed that age at symptom onset, attack frequency, arthritis, chest pain and having two exon 10 mutations were the strongest predictors of colchicine resistance. The score including these items had a sensitivity of 81.3% and a specificity of 49.1%. In the validation cohort (n = 671), its sensitivity was 93.5% and specificity was 53.8%. CONCLUSION: We developed a clinician-friendly and practical predictive score that could help us identify FMF patients with a greater risk of colchicine resistance and tailor disease management individually at the time of diagnosis.

Chronic non-bacterial osteomyelitis and immune checkpoint molecules.

OBJECTIVE: We aimed to investigate the plasma levels and cell surface expression of two checkpoint molecules, TIM-3 (T cell immunoglobulin and mucin domain-containing protein 3) and PD-1 (programmed cell death protein 1), in pediatric patients with chronic non-bacterial osteomyelitis (CNO). METHODS: Plasma samples of CNO patients were collected at diagnosis or during biologic agent treatment. Plasma levels of TIM-3 and PD-1 were measured using the sandwich enzyme-linked immunosorbent assay method, and the expression of the two immune checkpoint molecules on the cell surface was analyzed by isolating peripheral blood mononuclear cells by density gradient centrifugation technique. RESULTS: Twenty-seven patients with CNO (14 boys, 51.9%) and six healthy controls (3 boys, 50%) were enrolled in the study. There were no age differences between CNO patients and healthy controls (median age 14.5 vs. 13.5 years, respectively, p=0.762). Of the CNO patients, 18 were included at the time of diagnosis while 9 were receiving biologic treatment at enrollment. The median plasma PD-1 levels were significantly lower in the CNO group than in the healthy controls (p=0.011). However, no significant difference was found in the cellular expression of PD-1 and TIM-3 on CD3+CD4+ T cells in patients and healthy controls (p=0.083 and p=0.245, respectively). There was also no statistically significant difference in plasma TIM-3 levels of the patient and control groups (p=0.981). CONCLUSION: CNO is an autoinflammatory disease, and overall, our results suggest that T cell exhaustion may not be significant in CNO. Further research is needed to find out whether the immune checkpoints are mainly associated with autoimmunity but not autoinflammation. Key Points • The median plasma PD-1 levels were significantly lower in the CNO group than in the healthy controls. • No significant difference was found in the cellular expression of PD-1 and TIM-3 on CD3+CD4+ T cells in patients and healthy controls. • Our results suggest that T cell exhaustion may not be significant in CNO pathogenesis.

The Effect of Biologics in the Treatment of Multisystem Inflammatory Syndrome in Children (Mis-C): A Single-Center Propensity-Score-Matched Study.

Multisystem inflammatory syndrome in children (MIS-C) is a serious condition characterized by excessive inflammation that can arise as a complication of SARS-CoV-2 infection in children. While our understanding of COVID-19 and MIS-C has been advancing, there is still uncertainty regarding the optimal treatment for MIS-C. In this study, we aimed to compare the clinical and laboratory outcomes of MIS-C patients treated with IVIG plus corticosteroids (CS) to those treated with IVIG plus CS and an additional biologic drug. We used the propensity score (PS)-matching method to assess the relationships between initial treatment and outcomes. The primary outcome was a left ventricular ejection fraction of less than 55% on day 2 or beyond and/or the requirement of inotrope support on day 2 or beyond. We included 79 MIS-C patients (median age 8.51 years, 33 boys) followed in our center. Among them, 50 children (25 in each group) were allocated to the PS-matched cohort sample. The primary outcome was observed in none of the patients in the IVIG and CS group, while it occurred in eight patients in the IVIG plus CS and biologic group (p = 0.04). MIS-C is a disorder that may progress rapidly and calls for extensive care. For definitive recommendations, further studies, including randomized control trials, are required.

Feasibility of canakinumab withdrawal in colchicine-resistant familial Mediterranean fever.

OBJECTIVES: There is no consensus on canakinumab treatment tapering and discontinuation strategies in colchicine-resistant FMF patients. In this study, we aimed to establish a treatment management and discontinuation protocol in paediatric FMF patients treated with canakinumab. METHODS: Fifty-eight FMF patients treated with canakinumab were included. Since 2020, we have applied a protocol based on our experience whereby canakinumab is administered monthly in the first 6 months, followed by bimonthly for 6 months, and a final period of every 3 months (for 6 months). The patients were divided into two groups: 2012-2019 (group A) and 2020-2022 (group B). RESULTS: In group A (n = 33), the median duration of canakinumab treatment was 2.5 years [interquartile range (IQR) 1.9-3.7]. A total of 25 of 33 patients discontinued canakinumab after a median of 2.1 years (IQR 1.8-3.4). In two patients, canakinumab was restarted because of relapse. In group B (n = 25), canakinumab was discontinued in 18 patients at the end of 18 months. After a median follow-up of 0.8 years (IQR 0.6-1.1), two patients had a relapse and canakinumab treatment was reinitiated. The remaining 16 patients still have clinically inactive disease and are receiving only colchicine. When we compared the characteristics between groups A and B, there were no significant differences regarding demographics, clinical features, and outcomes. CONCLUSION: This is the largest study in the literature suggesting a protocol for discontinuing canakinumab in paediatric FMF patients. It was possible to discontinue canakinumab successfully in more than half of the patients in 18 months. Thus we suggest that this protocol can be used in paediatric FMF patients.

Pediatric mixed connective tissue disease versus other overlap syndromes: a retrospective multicenter cohort study.

Pediatric mixed connective tissue disease (MCTD) is a subgroup of overlap syndromes. We aimed to compare the characteristics and outcomes in children with MCTD and other overlap syndromes. All MCTD patients met either Kasukawa or Alarcon-Segovia and Villareal criteria. The patients with other overlap syndromes had the features of ≥ 2 autoimmune rheumatic diseases but did not meet MCTD diagnostic criteria. Thirty MCTD (F/M = 28/2) and thirty (F/M = 29/1) overlap patients were included (disease onset < 18 years). The most prominent phenotype at disease onset and the last visit was systemic lupus erythematosus (SLE) in the MCTD group; juvenile idiopathic arthritis and dermatomyositis/polymyositis, respectively, in the overlap group. At the last visit, systemic sclerosis (SSc) phenotype was more frequent among MCTD than overlap patients (60% vs. 33.3%; p = 0.038). The frequency of the predominant SLE phenotype had decreased (60% to 36.7%), while predominant SSc phenotype had increased (13.3% to 33.3%) during follow-up in MCTD patients. Weight loss (36.7% vs. 13.3%), digital ulcers (20% vs. 0), swollen hands (60% vs. 20%), Raynaud phenomenon (86.7% vs. 46.7%), hematologic involvement (70% vs. 26.7%), and anti-Sm positivity (29% vs. 3.3%) were more common, while Gottron papules (16.7% vs. 40%) were less frequent among MCTD than overlap patients (p < 0.05). A higher percentage of overlap patients achieved complete remission than MCTD patients (51.7% vs. 24.1%; p = 0.047). The disease phenotype and outcome differ between pediatric MCTD and other overlap syndromes where MCTD may be regarded as a more severe disease. Analyzing these patients could pave the way for early and effective treatment.

A Child with Refractory and Relapsing Anti-3-Hydroxy-3-Methylglutaryl-Coenzyme A Reductase Myopathy: Case-Based Review.

BACKGROUND/OBJECTIVE: Anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase (anti-HMGCR) myopathy is rare in children. Here, we present a boy with relapsing refractory anti-HMGCR myopathy along with a systematic literature review. CASE REPORT: 17-year-old boy with five years of muscle weakness, rash, high creatinine kinase (CK) levels, and muscle biopsy compatible with inflammatory myopathy was diagnosed with juvenile dermatomyositis. He was treated with corticosteroids, intravenous immunoglobulin (IVIG), and methotrexate. His muscle weakness improved with this treatment although never completely resolved. CK levels decreased from ∼15000 U/L to ∼3000 U/L. At the age of 15, muscle weakness relapsed after an upper respiratory tract infection; pulse corticosteroid treatment was administered. The re-evaluated muscle biopsy showed a necrotizing pattern and the HMGCR antibody was positive confirming anti-HMGCR myopathy when he was 16. The diagnostic delay was 50 months. Disease activity was monitored by Medical Research Council score, MRI and functional tests. Despite corticosteroids, methotrexate, IVIG, cyclosporine A, and rituximab therapies, muscle weakness improved only slightly during the first three months and remained stable afterwards.Results of the Literature Search:We identified 16 articles describing 50 children (76% female) with anti-HMGCR myopathy by reviewing the English literature up to March 1st, 2022. Proximal muscle weakness was the most common clinical symptom (70.8%). Corticosteroids (84.8%), IVIG (58.7%), and methotrexate (56.5%) were preferred in most cases. Complete remission was achieved in nine patients (28.1%). CONCLUSION: Diagnosis and management of children with anti-HMGCR myopathy are challenging. Complete remission is achieved in only one third of these patients. Imaging biomarkers may aid treatment.

Patients Without a Rheumatic Disease Diagnosis in a Pediatric Rheumatology Unit: Retrospective Analysis and Comparison Between Pre-pandemic and Pandemic Periods.

OBJECTIVE: Children with suspicious complaints of rheumatic diseases are generally referred to a pediatric rheumatologist. We aimed to evaluate the profile of patients referred to the pediatric rheumatology unit and were not diagnosed with a rheumatic disease and to assess the impact of the coronavirus disease-2019 pandemic on referral complaints. MATERIALS AND METHODS: All new outpatients who applied to the pediatric rheumatology department between March 2019 and February 2021 and were not diagnosed with rheumatic disease were included. We also compared the frequency of admission symptoms during the pre-pandemic (March 2019-February 2020) and pandemic periods (March 2020-February 2021). RESULTS: A total of 1089 patients without a rheumatic disease diagnosis (568 female, 52.2%; median age 10.0 years) were included in this study. The most common complaint for referral was prolonged or recurrent fevers (13.4%) followed by anti-nuclear antibody positivity (13.1%), arthralgia (13.0%), skin findings (7.5%), and the presence of heterozygous mutations in the Mediterranean fever gene (6.9%). During the pandemic year, the number of patients referred for back pain increased significantly (P = .028). A total of 682 of 1089 patients were consulted from other departments in our center (62.6%). Of these, the most frequent consultation request was from general pediatrics (43.6%). The rheumatic disease was excluded in 11.3% of the patients. CONCLUSION: Prolonged or recurrent fever and anti-nuclear antibody positivity were the most frequent complaints of referrals to a pediatric rheumatology unit in patients who did not have a rheumatic disease. The rate of back pain was more common in children during the pandemic period.

Report of 2 pediatric cases with atypical Cogan's syndrome and a systematic review.

Cogan's syndrome (CS) is a rare inflammatory disease characterized by interstitial keratitis or uveitis, vestibular impairment, and progressive hearing loss, commonly bilateral. Although glucocorticoids are fundamental treatment options, in most cases, hearing loss gradually worsens. Herein we report 2 pediatric cases of CS who were treated with corticosteroids and methotrexate. One patient had a cochlear implant, and the hearing of the other patient improved with treatment. Also, a systematic literature review was conducted for articles including pediatric CS patients. In the literature, 34 articles describing 44 pediatric patients with CS were identified. Sudden hearing loss (95.3%) and ocular symptoms (92.5%) were the most common manifestations in these patients. Also, aortic involvement was present in 19.5% of patients in the literature. Otorhinolaryngologists, ophthalmologists, and pediatricians should collaborate to diagnose and manage CS to prevent progressive hearing loss and eye involvement.

Rice bodies in children with rheumatic disorders: A case series and systematic literature review.

OBJECTIVES: Rice body (RB) formation is an uncommon inflammatory process seen in systemic disorders. In this study, we aimed to assess characteristic features of RBs in pediatric patients. METHOD: We retrospectively evaluated pediatric patients who underwent joint/extremity magnetic resonance imaging. A systematic literature review was conducted for articles including children with RBs. RESULTS: We found 24 patients (median age 6.1 years; F/M = 2.4) with RBs [23 with juvenile idiopathic arthritis (JIA) and one with arthralgia]. The most prevalent location for RBs was the knee joint (75%). RBs were most frequently seen as diffuse multiple millimetric structures. In three out of five patients with follow-up magnetic resonance imaging, resolution or regression of RBs was observed without surgical intervention. Our literature search identified 13 pediatric patients with RBs. Most (84.6%) had JIA, and the knee joint (71.4%) was the most commonly affected joint. Surgery was preferred in our 3 patients (12.5%) and 10 literature patients (83.3%) in the treatment. CONCLUSION: Our results showed that RBs were most commonly detected in the knee joint, and most cases were secondary to JIA. Although surgery is used as a treatment option, we observed that RBs can occasionally disappear during follow-up without surgical intervention.

A new tool supporting the diagnosis of childhood-onset Behçet's disease: venous wall thickness.

OBJECTIVES: The lower extremity venous wall thickness (VWT) of Behçet's disease (BD) patients was reported to be significantly increased in adults, suggesting its use for the support of BD diagnosis. This prospective study aimed to investigate the lower extremity VWT in childhood-onset definite and incomplete BD patients and compare it to healthy age-matched controls. METHODS: Paediatric patients classified with BD according to the 2015 international paediatric BD criteria in our centre were included in the study. Intima-media thickness of the lower extremity veins to evaluate VWT was measured by ultrasonography, including common femoral vein (CFV), femoral vein (FV), vena saphena magna, vena saphena parva and popliteal vein (PV). RESULTS: In this cross-sectional study, VWT was measured in 35 patients (63% male) and 27 healthy controls (55% male). Thirteen (37%) of 35 patients met the criteria for the diagnosis of BD. The remaining 22 (63%) had incomplete BD and met two criteria. The median VWT values of both definite and incomplete BD patients were significantly higher than the control group in all veins on both sides. Regarding the best cut-off values of VWT for all lower extremity veins, the sensitivity rates were between 63% and 86%, while specificity rates were between 71% and 100%. CONCLUSION: Increased VWT was present not only in BD patients with vascular involvement but also in those without. We suggest that VWT may be a new criterion in supporting the diagnosis of childhood BD both in definite and incomplete BD patients.

Hypersensitivity to Biological Treatments in Juvenile Idiopathic Arthritis: How Should It Be Managed?

Juvenile idiopathic arthritis (JIA) is one of the most frequent diseases in the practice of pediatric rheumatology. JIA treatments have been modified and improved with the use of biological drugs along with technological innovations. However, different types of hypersensitivity reactions to biological drugs have also been reported. Anaphylaxis and infusion reactions occurring during the intravenous infusion require a critical approach in the acute period. On the other hand, the detection of drug-related late-type reactions and the development of antibodies to the agent highlight the need for an understanding of the drug-induced etiology to prevent the patient from continuing the treatment with the culprit drug. The chronic disease process, concomitant immune dysregulation, and multiple drug use may result in these hypersensitivity reactions. In this review, the hypersensitivity reactions to the biological treatments used in patients with juvenile idiopathic arthritis and the management of these conditions are discussed.

Treatment of childhood-onset Takayasu arteritis: switching between anti-TNF and anti-IL-6 agents.

OBJECTIVES: Biologics are new treatment alternatives in Takayasu arteritis (TA), although data in childhood are limited. The aim of this study was to share our experience in seven childhood-onset TA patients who received a TNF-α inhibitor (adalimumab) or an IL-6 receptor inhibitor (tocilizumab) and the effect of switching therapy. METHODS: We retrospectively evaluated the medical treatment records of seven patients with TA, followed between August 2005 and January 2021 at the Pediatric Rheumatology Department of Hacettepe University Faculty of Medicine. RESULTS: The median age of patients was 14 (IQR 4) years, and six were female. All of the patients had severe disease and high acute-phase reactants. The patients initially received only steroids or steroids+CYC. Prednisone was decreased, and biologic agents were started once the acute phase reactants decreased, and the Indian Takayasu Activity Score (ITAS) returned to normal. Initially, four patients received tocilizumab (TCZ) [median 25.5 (IQR 41) months] and three patients received adalimumab (ADA) [median 13 (IQR 31) months]. However, due to the progression of MR angiography findings or persistent elevation in acute-phase reactants, the biologic agents were switched from TCZ to ADA in four patients and from ADA to TCZ in three patients. The patients' median follow-up time after changing was 50 (IQR 77) months, and median ITAS was evaluated as '0' after 2 (IQR 4) months. CONCLUSIONS: In conclusion, both TNF-α and IL-6 inhibitors are effective alternatives in treating patients with childhood-onset TA. However, prospective randomized controlled trials are needed for the comparison of their effectiveness.

The performances of the ILAR, ASAS, and PRINTO classification criteria in ERA patients: a comparison study.

BACKGROUND: Enthesitis-related arthritis (ERA) could be considered the pediatric equivalent of ankylosing spondylitis in adults albeit with certain significant differences. We aim to evaluate the sensitivity and specificity of the International League of Associations for Rheumatology (ILAR), the Assessment of Spondyloarthritis International Society (ASAS), and the preliminary Pediatric Rheumatology International Trials Organization (PRINTO) classification criteria in ERA patients. METHOD: The medical records of ERA patients who were followed up between January 2005 and September 2020 have been analyzed. The control group consisted of patients with oligoarticular JIA (n = 146), polyarticular JIA (n = 55), and psoriatic arthritis (n = 20). RESULTS: This retrospective study included 108 ERA (73.1% male) and 221 control patients (25.8% male). The median age at diagnosis for ERA and control patients were 12.5 and 4.0 years, respectively (p < 0.001). Arthritis was observed more frequently in the control group at diagnosis and in the follow-up (p < 0.001 for both), while enthesitis, sacroiliac joint tenderness, and inflammatory back pain were more common in the ERA group both at diagnosis and in the follow-up (p < 0.001 for all). In sacroiliac imaging, 70.1% of ERA patients had positive findings suggestive of sacroiliitis at diagnosis and 78% in the follow-up. The sensitivities of ILAR, PRINTO, ASAS criteria for axial SpA, and peripheral SpA at diagnosis were 74.0%, 57.4%, 21.3%, and 85.1%, respectively which increased to 82.4%, 78.7%, 35.1%, and 92.5%, respectively at follow-up. The specificities were 100%, 100%, 99.1%, and 90.9%, respectively at both diagnosis and follow-up. CONCLUSION: The ASAS criteria for peripheral SpA were the most sensitive while ILAR and the preliminary PRINTO criteria were the most specific criteria for classifying ERA patients. KEY POINTS: The ASAS criteria for peripheral SpA were the most sensitive criteria for classifying ERA patients. The use of ASAS axial SpA criteria may provide early detection of axial involvement.

Differences and similarities of multisystem inflammatory syndrome in children, Kawasaki disease and macrophage activating syndrome due to systemic juvenile idiopathic arthritis: a comparative study.

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.

IgG4-related disease in pediatric patients: a single-center experience.

OBJECTIVE: Immunoglobulin G4-related disease (IgG4-RD) is a systemic, immune-mediated, and fibroinflammatory disease that can affect almost any organ system. We aimed to present our single-center experience of pediatric patients with IgG4-RD, a rare disease in children. METHODS: Pediatric patients diagnosed with IgG4-RD at the Hacettepe University between June 2014 and September 2020 were evaluated retrospectively. Patients with definite, probable, or possible diagnosis of IgG4-RD were included. RESULTS: A total of eight patients with a median age of 13.4 (IQR 9.5-15.0) years were included in the study. Clinical presentations were IgG4-related ophthalmic disease in six patients, IgG4-related lymphadenopathy in one patient, and IgG4-related sialadenitis and lymphadenopathy of several lymph nodes accompanied by pancreatitis, ulcerative colitis, and pulmonary manifestations in one patient. Elevated serum IgG4 was detected in three of eight patients (37.5%). The main histopathological feature was fibrosis and lymphoplasmacytic infiltrates. Corticosteroids were used as first-line treatment in almost all patients with or without steroid-sparing agents. Azathioprine, methotrexate and rituximab were used as steroid-sparing agents. Relapse occurred in two of seven patients. Radiotherapy was used as the last resort in one patient with severe orbital disease. CONCLUSION: IgG4 RD mainly presents with orbital manifestations in pediatric population but has wide phenotypic clinical variability. Although rare, early recognition and treatment are essential for a better outcome in these patients.

Challenges in diagnosing COVID-19 related disease in pediatric patients with rheumatic disease.

OBJECTIVES: Multisystem inflammatory syndrome in children (MIS-C) is a rare but severe condition associated with coronavirus disease 2019. Here we aimed to raise awareness for the symptoms of MIS-C in patients with rheumatic diseases, emphasizing the challenges of the differential features. METHODS: We retrospectively evaluated the demographic and clinical characteristics, laboratory and imaging findings, treatments, and outcomes of six MIS-C patients with previous rheumatic disease. RESULTS: Three of the patients had familial Mediterranean fever (FMF), one had juvenile dermatomyositis, one had systemic juvenile idiopathic arthritis (JIA), and another patient had oligoarticular JIA. All FMF patients presented with fever and abdominal pain, two also had chest pain. The patient with systemic JIA presented with fever, rash, and myalgia. All patients had elevated inflammatory markers and high d-dimer levels. Chest imaging of two FMF patients showed infiltrations compatible with pneumonia. One FMF patient had mildly decreased systolic functions with a shortening fraction of 48% in his echocardiography. Intravenous immunoglobulin and methylprednisolone were administered to all patients. Anakinra was given to four patients. CONCLUSIONS: Clinical and laboratory signs of MIS-C may overlap with the findings of various rheumatic diseases, and this may cause a delay in diagnosis.