Drug-induced lupus erythematosus in childhood: Case-based review.

BACKGROUND: Drug-induced lupus erythematosus (DILE) is the development of lupus-like syndrome following a drug exposure. DILE has been reported less frequently among children than adults. METHODS: In this study, we present four children with DILE and similar published cases through a systematic literature review. RESULTS: We report four children (three girls and one boy) who developed DILE associated with the use of topiramate, doxycycline, etanercept, and ethosuximide. Three of them were positive for anti-histone antibodies. In all patients, the drug was discontinued and symptoms resolved completely. The literature review revealed 48 articles describing 61 children with DILE. In the evaluation of 65 patients (our 4 patients and 61 patients from the literature), the most frequently reported drugs associated with DILE were ethosuximide (n = 13) and minocycline (n = 12). Fever (n = 33), arthralgia (n = 31), rash (n = 30), and arthritis (n = 29) were the most common clinical manifestations. Antinuclear antibody (ANA) was positive in 93.5% of patients and anti-histone antibodies were detected in 72.2% of the patients. As for treatment, the responsible drug was discontinued in all patients, and corticosteroids were initiated in 53.3%. Improvement was achieved in 92.0% of patients. CONCLUSION: For children presenting with SLE features, proper drug history is crucial since DILE may be more frequent than anticipated. An association of the relevant drug with the symptoms, and resolution of symptoms on drug withdrawal provides evidence for the diagnosis of DILE.

Rhupus syndrome in children: A multi-center retrospective cohort study and literature review.

OBJECTIVE: In this study, we aimed to evaluate the characteristics of pediatric rhupus patients including all the related series in the literature. METHODS: Thirty pediatric patients with rhupus syndrome from 12 different centers in Turkey were included in this study. The literature was also reviewed for pediatric patients with rhupus syndrome. RESULTS: The most prominent phenotype of these 30 patients was juvenile idiopathic arthritis (JIA) (60%) at the disease onset and SLE (73.3%) at the last visit. Major SLE-related organ involvements were skin (80%), hematological system (53.3%), and kidney (23.3%). Arthritis was polyarticular (73.3%), asymmetric (66.7%), and erosive (53.3%) in most patients. Hydroxychloroquine (100%), glucocorticoids (86.7%), and mycophenolate mofetil (46.7%) were mostly used for SLE, while glucocorticoids (76.6%), methotrexate (73.3%), and nonsteroidal anti-inflammatory drugs (NSAIDs) (57.6%) were mainly preferred for JIA. Our literature search revealed 20 pediatric patients with rhupus syndrome (75% were RF positive). The most prominent phenotype was JIA (91.7%) at the disease onset and SLE (63.6%) at the last visit. Major SLE-related organ involvements were skin (66.7%), hematological system (58.3%), and kidney (58.3%). Arthritis was polyarticular (77.8%), asymmetric (63.6%), and erosive (83.3%) in most patients. Glucocorticoid (100%), hydroxychloroquine (76.9%), and azathioprine (46.2%) were mostly used for SLE, while methotrexate (76.9%) and NSAIDs (46.2%) were mainly preferred for the JIA phenotype. CONCLUSION: Our study is the largest cohort in the literature evaluating pediatric rhupus cases. Most of the pediatric patients had polyarticular, asymmetric, and erosive arthritis, as well as organ involvements associated with SLE, including the skin, hematological system, and kidney.

Evaluation of clinical outcomes in systemic juvenile idiopathic arthritis patients treated with biological agents in Turkey: the TURSIS study.

OBJECTIVES: Biological drugs are one of the most effective treatment methods for systemic juvenile idiopathic arthritis (SJIA) and can significantly prevent morbidity and mortality. This study aimed to evaluate the efficacy and safety of biologics in patients with SJIA and provide real-life data that might help improve the outcomes. METHODS: TURSIS was a retrospective multicentre study carried out in patients with SJIA for whom a biological treatment had been initiated between 1st March 2013 and 30th December 2018. Data include patients' characteristics, laboratory-clinical results, outcomes, and safety-related variables. The 24-month follow-up data of the patients and the efficacy and safety of biological drugs were evaluated. RESULTS: 147 patients were enrolled. The clinical course of the disease was as follows; it was monocyclic in 38.1%, polycyclic in 49%, and persistent in 12.9% of patients. First-choice biologics were interleukin (IL)-1 blockers in the majority of patients (56.5%), followed by the anti-IL-6 (25.2%) and anti-TNF-alpha drugs (18.4%). Anakinra was the most preferred biologic agent in patients with macrophage activation syndrome (MAS), and tocilizumab was used more frequently in patients with persistent type (p=0.000 and p=0.003). The most frequent switch rate was seen in patients receiving anakinra (n=40/68, 58.8%), and it was most frequently switched to canakinumab (n=32/40, 80%). Better physician's global assessment scores were achieved in patients treated with anakinra in Month 3, compared to other treatments (p=0.04). CONCLUSIONS: The results of our study support the efficacy of biological drugs in particular anti-IL-1 and anti-IL-6 drugs, in the treatment of SJIA. These treatments resulted in improvement in activity of disease and provide a considerable decrease in the frequency of MAS.

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.

Comparison of EULAR/PRINTO/PReS Ankara 2008 and 2022 ACR/EULAR Classification Criteria for Granulomatosis with Polyangiitis in Children.

OBJECTIVE: Granulomatosis with polyangiitis (GPA) is an antineutrophil cytoplasmic antibody-associated vasculitis. The 2022 American College of Rheumatology/European Alliance of Associations for Rheumatology (ACR/EULAR)-endorsed classification criteria for GPA was derived using data only from adult patients. We aimed to assess the performance of the ACR/EULAR classification criteria for GPA in pediatric patients and compare it with the EULAR/Pediatric Rheumatology International Trials Organization (PRINTO)/Pediatric Rheumatology European Society (PReS)-endorsed Ankara 2008 criteria for GPA. METHODS: Retrospective data of pediatric patients with GPA in 20 centers from 9 countries were evaluated. The diagnosis of GPA was made according to the expert opinion. The sensitivity, specificity, positive predictive value, and negative predictive value of the criteria sets were evaluated. RESULTS: The study included 77 patients with GPA and 108 controls (immunoglobulin A vasculitis (n = 44), Takayasu's arteritis (n = 20), microscopic polyangiitis (n = 16), polyarteritis nodosa (n = 14), Behçet's disease (n = 12), eosinophilic granulomatosis with polyangiitis (n = 1), and Cogan's syndrome (n = 1)) with a median age of 17.8 and 15.2 years, respectively. Of patients with GPA, constitutional symptoms (85.7%) and ear-nose-throat involvement (79.2%) were the most common presentations. In the GPA group, 73 patients fulfilled the Ankara 2008 criteria and 69 the ACR/EULAR classification criteria. Sensitivities of the Ankara 2008 criteria and the ACR/EULAR classification criteria were 94.8% and 89.6%, while specificities were 95.3% and 96.3%, respectively. No significant difference was found between sensitivities and specificities of both classification criteria (p= 0.229 and p= 0.733, respectively). CONCLUSION: In children, both the ACR/EULAR and EULAR/PRINTO/PReS Ankara 2008 classification criteria for GPA perform well and similarly.

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.

Comparison of IVIG resistance predictive models in Kawasaki disease.

BACKGROUND: We aimed to compare the ten different scores (by Kobayashi, Egami, Harada, Formosa, Sano, Piram et al., Wu et al., Yang et al., Tan et al., and Kanai et al.) to assess their performance in predicting IVIG resistance in Turkish children. METHODS: Complete and incomplete KD patients diagnosed with KD at Hacettepe University between June 2007 and September 2019 were evaluated retrospectively. RESULTS: A total of 129 patients, 79 boys (61.2%), with a median age 36 (IQR 19.5-57.0) months were evaluated. Sixteen patients (12.4%) had IVIG resistance. Sensitivity was low for all the ten scores. Tan, Sano, and Egami predictive models had the highest specificity (97.3, 89.4, 86.7%, respectively). Almost all scoring systems distinguished the group of patients with low risk for IVIG resistance but could not differentiate IVIG-resistant patients. Multivariate analysis for the laboratory features showed that platelet count <300 × 109/L and GGT serum levels were independent risk factors for IVIG resistance (OR: 3.896; 95% CI: 1.054-14.404; p = 0.042 and OR: 1.008; 95% CI: 1.001-1.015; p = 0.050). CONCLUSIONS: The current scoring systems had a low sensitivity for predicting the risk for IVIG resistance in Turkish children. On the other hand, increased serum GGT levels and low platelet count were risk factors for predicting IVIG resistance. IMPACT: Intravenous immunoglobulin (IVIG) resistance may be observed in 10-20% of patients diagnosed with Kawasaki disease. Coronary artery involvement is more frequent in IVIG-resistant patients. It is important to predict the patients who might develop IVIG resistance to improve prognosis. The performance of the IVIG resistance predictive models in Kawasaki disease in our population is limited due to the low sensitivity.

The challenges in diagnosing pediatric primary antiphospholipid syndrome.

Pediatric primary antiphospholipid syndrome (APS) is a very rare disease with significant distinctions from the APS in adults. Herein, we present our experience in the diagnosis and treatment of six pediatric primary APS patients, who met the updated Sapporo criteria for the APS diagnosis. One of them was also diagnosed as having probable catastrophic APS (CAPS) due to the involvement of three different organ systems simultaneously. Besides vascular involvement, four patients had thrombocytopenia, one had psychiatric disorder, and one had chorea and valvular heart disease. All patients received immunosuppressive treatment along with long-term anticoagulation therapy. Specific neurologic and hematologic manifestations that are not part of the classification criteria can be seen in children with primary APS. Therefore, using the adult criteria for diagnosing pediatric APS may result in missed or delayed diagnoses in children.

Probiotic use in the prophylaxis of periodic fever, aphthous stomatitis, pharyngitis, and adenitis (PFAPA) syndrome: a retrospective cohort study.

Periodic fever, aphthous stomatitis, pharyngitis, and adenitis (PFAPA) syndrome is an autoinflammatory recurrent fever syndrome that mainly affects children. Probiotics are currently used to prevent upper respiratory tract infections and flares of diseases associated with immune dysregulation. We aimed to evaluate the response to probiotic treatment in PFAPA patients. Patients with PFAPA syndrome who received probiotics and were followed between July 2019 and July 2021 were included in this retrospective study. Demographic and clinical features and response to probiotics were assessed. Twenty out of 111 children with PFAPA syndrome (F/M:1) were included. The median (min-max) ages at symptoms onset and diagnosis were 24 (3-72) and 51.5 (11-120) months, respectively. All 20 patients received probiotics during the disease course. The probiotic preparation they received included a combination of two lactobacilli as Lactobacillus plantarum HEAL9 (Lp HEAL9) and Lactobacillus paracasei 8700:2 (Lpa 8700:2). The median age at probiotic onset was 60 (33-192) months, while the duration of probiotic use was 4.5 (3-19) months. All patients except one experienced a decrease in attack frequency with probiotic use. After probiotic treatment, the median number of episodes during 3 months decreased from 3 to 1 (p < 0.001). Eight (40%) patients had no attacks during the 3 months after probiotic initiation. And, 5 (45%) of 11 patients who had ≥ 1 attacks on probiotics mentioned that the attack severity decreased significantly after probiotic initiation. Our results suggest that probiotic strains Lactobacillus plantarum HEAL9 and Lactobacillus paracasei 8700:2 could be beneficial in PFAPA patients by decreasing the attack frequency.

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.

Impact of the COVID-19 pandemic on the frequency of the pediatric rheumatic diseases.

The impact of the COVID-19 pandemic, and implemented restrictions on the frequency of pediatric rheumatic diseases remain unknown, while they have probably prevented common infections in children. We present the effects of the COVID-19 on our pediatric rheumatology practice in a main referral center. We retrospectively reviewed the medical records of patients presenting to pediatric rheumatology department in 4 years before March 2020 and compared it to the pandemic year (March 2020-March 2021). Since there was an overall decrease in patient numbers, we calculated the percentage according to the total number of that year. A total of 32,333 patients were evaluated. The mean annual number of patients decreased by 42% during the COVID-19 pandemic. When follow-up visits (25,156) were excluded, there were 2818 new diagnoses of rheumatic diseases. In the pre-pandemic period, familial Mediterranean fever (FMF) (n = 695, 28.1%) was the most frequent, whereas in the pandemic period multisystem inflammatory syndrome in children (MIS-C) (n = 68, 19.2%) was the most common diagnosis. There were no significant differences in the percentages of juvenile idiopathic arthritis, autoimmune diseases, rare autoinflammatory diseases, and other vasculitides. However, there was a significant decrease in patients diagnosed with FMF, IgA vasculitis (IgAV), acute rheumatic fever (ARF), classic Kawasaki disease (KD), and macrophage activation syndrome (MAS) (all p < 0.05). During the pandemic year, the percentage of most common diseases did not differ. On the other hand, we suggest that the decreases in IgAV, KD (classic), and MAS, which parallels the decrease in ARF, confirm the role of infections in the pathogenesis for these diseases.

The clinical course of SARS-CoV-2 infection among children with rheumatic disease under biologic therapy: a retrospective and multicenter study.

The effects of biological disease-modifying antirheumatic drugs (bDMARDs) in the clinical course of COVID-19 on children with underlying rheumatologic diseases have not been fully demonstrated. To evaluate the course of COVID-19 infection in patients with rheumatic disease receiving bDMARD treatment. This was a retrospective, multicenter study conducted in pediatric patients infected by SARS-CoV-2 and under bDMARDs therapy. The study population consisted of 113 patients (72 female/41 male). The mean age of the patients was 12.87 ± 4.69 years. The primary diagnosis of the cohort was as follows: 63 juvenile idiopathic arthritis, 35 systemic autoinflammatory diseases, 10 vasculitides, and five cases of connective tissue diseases. The mean duration of the primary disease was 4.62 ± 3.65 years. A total of 19 patients had additional comorbid diseases. Thirty-five patients were treated with canakinumab, 25 with adalimumab, 18 with etanercept, 10 with infliximab, nine with tocilizumab, six with rituximab, four with anakinra, three with tofacitinib, and one with abatacept. The median exposure time of the biological drug was 13.5 months. Seventy-one patients had symptomatic COVID-19, while 42 were asymptomatic. Twenty-four patients required hospitalization. Five patients presented with MIS-C. The hospitalized patients were younger and had a shorter duration of rheumatic disease compared to ambulatory patients, although the difference was not statistically significant. Steroid usage, presence of fever, and dyspnea were more common among the hospitalized patients. A worsening in the course of both COVID-19 and current disease was not noticed under bDMARDs, however, to end with a strong conclusion multicentric international studies are required.

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.

Clinical course of COVID-19 infection in paediatric familial Mediterranean fever patients.

OBJECTIVE: To evaluate the course of coronavirus-19 (COVID-19) infection in paediatric familial Mediterranean fever (FMF) patients and to investigate the risk factors for COVID-19 infection. METHODS: Medical records of 100 consecutive paediatric FMF patients and their COVID-19 infection status were evaluated. Age- and gender-matched control group consisted of 51 patients with positive results for severe acute respiratory syndrome coronavirus 2. RESULTS: Twenty-five of 100 paediatric FMF patients were detected to have COVID-19 infection. A history of contact with a COVID-19 case was present in ∼95% of patients in both the FMF and control groups with COVID-19 infection. Asymptomatic infection was detected in two patients in the paediatric FMF group (8.0%) and 17 patients in the control group (33.3%) (P = .017). Mild disease was observed in 23 paediatric FMF patients (92.0%) and 28 control patients (54.9%) (P = .001), whereas moderate disease was present in only 6 control patients (11.7%) (0 vs 11.7%, P = .074). Severe or critical disease was not observed in any patients. CONCLUSION: Paediatric FMF patients receiving colchicine had no moderate COVID-19 disease compared to the control group. We suggest that colchicine use may tune down the severity of the disease even if it does not prevent COVID-19 infection.

Is Takayasu's arteritis more severe in children?

OBJECTIVES: Takayasu's arteritis (TAK) is a chronic vasculitis, affecting predominantly the aorta and/or its major branches. The aim of this study was to compare the differences between childhood and adult onset TAK. METHODS: We retrospectively evaluated 179 TAK patients followed between August 2005 and July 2019. Demographic characteristics, laboratory features, disease activity, echocardiographic data at diagnosis and treatment regimens in the disease course were compared between the paediatric and adult onset patients. RESULTS: Twenty-five paediatric-onset (<18 years of age at diagnosis) and 154 adult-onset patients (≥18 years of age at diagnosis) were enrolled. The mean age at diagnosis for children and adults were 13.6±4 and 35.6±13, respectively. Paediatric onset TAK patients had more intense inflammation at the time of diagnosis reflected in their clinical findings. Acute phase reactants were high in all paediatric patients and significantly higher in patients with paediatric-onset TAK (p=0.006 and p=0.005, respectively). Abdominal predominant disease was more common in the paediatric group, in contrast, focal disease and aortic arch predominant disease were more common in the adult group. Ascending aortic dilatation, left ventricular hypertrophy and moderate-severe aortic insufficiency were more frequent in echocardiography findings of paediatric onset TAK patients. In comorbidities, hypertension was more common in paediatric TAK patients during follow-up, whereas cerebrovascular disease was more common in adult patients. CONCLUSIONS: Our paediatric onset TAK patients presented with a more severe inflammation and more widespread vascular involvement. Multicentre studies from different geographic areas are needed to verify our observation and understand the underlying causes.

Comorbidities in familial Mediterranean fever: analysis of 2000 genetically confirmed patients.

OBJECTIVES: FMF is the most common periodic fever syndrome, characterized by recurrent episodes of fever and serosal inflammation accompanied with high acute phase reactants. The analysis of possible comorbidities is important to understand the impact of these conditions on clinical care and whether they share a common aetiological pathway. In this study, we aimed to evaluate the comorbidities associated with FMF patients in a large genetically diagnosed cohort. METHODS: We retrospectively evaluated the medical and genetic records of FMF patients who were followed up by rheumatologists in Hacettepe University for 15 years. The FMF patients who had homozygous or compound heterozygous mutations were included in the study. Comorbidities associated with FMF were divided into three groups: (i) comorbidities directly related to FMF, (ii) comorbidities due to increased innate inflammation, and (iii) comorbidities that were regarded as being incidental. RESULTS: A total of 2000 patients with a diagnosis of FMF were enrolled in the study. Among them 636 were children (31.8%) and M694V was the most common mutation in patients with associated inflammatory conditions. The frequency of AS, Iga Vasculitis (Henoch-Schönlein purpura), juvenile idiopathic arthritis, polyarteritis nodosa, multiple sclerosis and Behçet's disease were increased in patients with FMF when compared with those in the literature. CONCLUSION: This study represents the largest genetically confirmed cohort and compares the frequencies with existing national and international figures for each disease. The increased innate immune system inflammation seen in FMF may be considered as a susceptibility factor since it predisposes to certain inflammatory conditions.

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.

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.