To assess the 2022 American College of Rheumatology (ACR)/EULAR classification criteria for antineutrophil cytoplasmic antibody-associated vasculitis (AAV) in children with chronic small-to-medium vessel vasculitis. A cohort of 574 patients, identified by physician's diagnosis (MD-diagnosis) in A Registry of Childhood Vasculitis, was classified by computation of registry data as having granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), or eosinophilic GPA after applying (1) ACR/EULAR AAV criteria and (2) pediatric-adapted European Medicines Agency (Ped-EMA) classification algorithm (incorporating Ankara GPA criteria). Venn diagrams compared the resulting GPA and MPA cohorts with MD-diagnosis. Sensitivity and specificity of criteria for GPA were evaluated against MD-diagnosis. Fisher exact test evaluated differences in the frequencies of individual clinical features in GPA versus MPA. Comparing ACR/EULAR criteria against the Ped-EMA algorithm for classifying AAV, more patients were classified as GPA or MPA (n=396 vs 360, respectively), fewer had GPA (n=261 vs 288, respectively), more had MPA (n=135 vs 72, respectively), and fewer GPA cases coclassified as MPA (12% vs 28%, respectively); there were more differences between GPA and MPA in Pediatric Vasculitis Activity Score-defined clinical features (n=14 vs 10, respectively). When classifying GPA by ACR/EULAR or Ankara criteria, sensitivity (74.5% vs 72.1%, respectively) was comparable, and specificity for ACR/EULAR criteria (93.9% vs 79.9%, respectively) was improved. The 2022 ACR/EULAR classification criteria for AAV perform at least as well as previous pediatric criteria and provide categorical MPA criteria where none existed previously; the criteria for GPA and MPA now specifically differentiate each other, with more differences between them in the frequencies of clinical features. Our findings support the preferential use of ACR/EULAR over Ankara criteria for GPA in pediatrics.

Kawasaki disease (KD) is an acute systemic vasculitis of childhood and the leading cause of acquired heart disease in children in developed countries. Infants frequently present with incomplete disease, resulting in delayed diagnosis and increased risk of coronary complications. Data on KD from Africa, particularly Ethiopia, remain extremely limited. This is the first reported case of incomplete KD in an Ethiopian infant. A fatal case of a six-month-old Ethiopian female infant with missed incomplete Kawasaki disease is reported. At four months of age, she presented with nine days of unexplained fever and markedly elevated inflammatory markers but lacked the classic clinical features of KD. The diagnosis was not considered and she was empirically treated for presumed infectious causes. Two months later she presented in cardiogenic shock. Echocardiography revealed giant coronary aneurysms with intraluminal thrombosis and severely depressed left ventricular systolic function. Despite intensive care support, the patient died within 12 hours of admission. This case highlights the devastating consequences of missed and delayed recognition of incomplete KD in young infants. Clinicians must maintain a high index of suspicion for KD in infants with prolonged unexplained fever and elevated inflammatory markers, even in the absence of classic clinical features. Strict adherence to established diagnostic algorithms is essential to prevent catastrophic cardiac complications, particularly in low-resource settings where awareness of KD remains limited.

IntroductionSCUBE1 and SCUBE2 are vascular-associated proteins involved in endothelial processes. Although these molecules have been investigated in several vascular and inflammatory disorders, their potential involvement in pediatric immunoglobulin A vasculitis (IgAV) has not yet been elucidated. IgAV is the most common systemic vasculitis of childhood, characterized by leukocytoclastic vasculitis and immune complex deposition, yet its biomarker profile remains incompletely understood. We explored the association of SCUBE proteins with inflammatory markers in pediatric IgAV.MethodsTwenty-six children diagnosed with IgAV according to the Ankara 2008 criteria were prospectively included. Serum SCUBE1, SCUBE2, interleukin (IL)-1, IL-6, and tumor necrosis factor alpha (TNFα) levels were measured during both the active and recovery phases of the disease. Findings were compared with age- and sex-matched healthy controls using enzyme-linked immunosorbent assay (ELISA) methods.ResultsIL-1 and IL-6 levels were significantly elevated in patients during the active phase compared with healthy controls (p = 0.006 and p = 0.01, respectively), supporting their role in acute inflammation. SCUBE1 and SCUBE2 levels did not significantly differ between active and recovery phases. However, SCUBE2 levels were significantly lower in the recovery phase than in controls (p = 0.008), suggesting potential downregulation following acute inflammation.ConclusionsOur findings indicate that SCUBE2 may be more closely related to late-stage vascular stabilization or tissue repair mechanisms rather than acute inflammatory activity in IgAV. This preliminary finding suggests that SCUBE2 may be associated with post-inflammatory processes; however, further studies are required to clarify its clinical relevance.

Background: Immunoglobulin A (IgA) vasculitis is the most common vasculitis of childhood. This study aimed to evaluate the demographic characteristics, clinical manifestations, laboratory findings, prognostic features, differential diagnoses, and treatment approaches of children diagnosed with IgA vasculitis in our clinic. Methods: This retrospective study included children diagnosed with IgA vasculitis between February 2020 and November 2025. Demographic, clinical, laboratory, imaging, biopsy, and treatment data were obtained from medical records. Results: Seventy-four patients were included (mean age: 7.7 ± 3.3 years; 60.8% female), with admissions occurring most frequently in autumn and winter. A preceding infection within the last two weeks was present in 78% of patients. Epstein-Barr virus IgM positivity was detected in three patients and Cytomegalovirus IgM positivity in three patients. Joint, gastrointestinal, and renal involvement were observed in 35, 46, and 30 patients, respectively; testicular involvement was detected in two patients and pneumonic infiltration in one patient. Severe gastrointestinal involvement was observed in six patients (melena in four and intussusception in two). Extensive rheumatologic testing revealed no additional pathology, and skin punch biopsy demonstrated findings consistent with IgA vasculitis in all cases. Corticosteroids were required in 44 patients due to gastrointestinal or renal involvement, or persistent disease. Conclusions: Although IgA vasculitis is generally self-limiting, careful clinical monitoring is essential due to the risk of acute gastrointestinal, testicular, and renal complications, and its potential to mimic other causes of acute abdomen before purpura onset. Extensive rheumatologic testing, broad infectious screening and skin biopsy did not provide additional diagnostic or follow-up value beyond clinical assessment.

Immunoglobulin A vasculitis (IgAV), also known as Henoch- Schönlein purpura (HSP), is the most common systemic vasculitis in childhood. Potential differences in demographic characteristics, clinical presentation, laboratory findings, and treatments approaches across age groups, remain poorly explored. To the best of our knowledge, no multicenter study in Latin America has systematically addressed these features. We aimed to assess demographic, clinical and laboratory features, and treatments in children versus adolescents with (IgAV)/ (HSP) in a large multicenter study. A multicenter study involving four tertiary centers evaluated 687 children and adolescents (≤ 18 years-old) with IgAV/HSP (EULAR/PRINTO/PRES classification criteria) at first 3 months after diagnosis. The charts were retrospectively assessed for demographic data, initial clinical manifestations, laboratory tests and treatments. Data were compared between children (< 10 years-old) and adolescents (≥ 10 years-old), according to WHO definition. IgAV/HSP was diagnosed in 599/687(87%) children [5.33(0.88–9.91) years-old] and 88/687(13%) adolescents [11.33(10-17.5) years-old]. The median duration of purpura/petechiae was significantly lower in children compared to adolescents [14(1-120) vs. 15(2–90) days, p = 0.04]. The frequency of persistent purpura/petechiae (≥ 6 weeks of duration) was significantly reduced in the former group (7.2% vs. 19.5%, p = 0.002), likewise the frequency of gastrointestinal bleeding (17% vs. 34.1%, p = 0.01) and proteinuria (49.7% vs. 84%, p = 0.002). In contrast, the frequencies of arthritis/arthralgia (82.7% vs. 73%, p = 0.03) and orchitis(16.6% vs. 4.8%, p = 0.04) were significantly higher in children. Further analysis of laboratory tests showed that the median value of serum IgA was significantly lower in children than in adolescents [179.1(40-1002.0) vs. 279.0(104.0-488.0) mg/dL, p = 0.01], whereas thrombocytosis was higher (40.1% vs. 23%, p = 0.007). Logistic regression demonstrated that persistent purpura/petechiae after IgAV/HSP diagnosis (OR = 18.337; 95%CI 1.245-270.137; p = 0.034) was the only independently associated variable with dependent variable (adolescent). In this large multicenter cohort, IgAV/HSP onset occurred rarely at adolescence, with a more prominent cutaneous involvement. Prolonged purpura/petechiae after IgAV/HSP diagnosis was associated with adolescent-onset IgAV/HSP, reinforcing the need for vigilant monitoring in this subgroup.

Kawasaki disease (KD) is an acute, self-limiting systemic vasculitis of early childhood and remains the leading cause of acquired heart disease in developed nations. Despite decades of investigation, its etiology and immunopathogenesis are still not fully understood. This review integrates nearly six decades of histopathological, epidemiological, and immunological research to examine infection-driven mechanisms underlying KD. Current evidence indicates that KD may result from a convergence of microbial and host factors: viral infections can trigger mucosal IgA-mediated immune activation; superantigens may induce T-cell receptor (TCR) Vβ-skewed cytokine release; conventional antigens appear to elicit oligoclonal adaptive immune responses consistent with infection-associated vasculitis; and gut microbiota dysbiosis may amplify systemic inflammation through disruption of intestinal barrier integrity and short-chain fatty acid metabolism. Rather than a single-pathogen infection, KD likely reflects infection-triggered immune dysregulation in genetically susceptible children. By contrasting these mechanistic hypotheses, this review highlights the need for longitudinal, multi-omics studies integrating metagenomic, transcriptomic, and serologic analyses to delineate causal microbial signatures, identify diagnostic biomarkers, and guide precision immunomodulatory strategies for this complex pediatric vasculitis.

Background: Henoch-Schonlein purpura (HSP) is the most common childhood vasculitis, primarily affecting children under 10 years. While typically self-limiting with a good prognosis, HSP can become life-threatening if multiple organs are involved. Early diagnosis was critical to prevent complications and ensure optimal outcomes. Objective: To highlight the diagnostic challenges of HSP when recurrent abdominal pain appeared with delayed onset of purpura and athralgia. Case: A 10-year-old male presented with abdominal pain, had been hospitalized, but after discharge, he developed red spots on his lower extremities and buttocks along with joint pain in his legs. As his abdominal pain recurred and worsened, he was readmitted. Physical examination revealed diffuse tenderness and palpable purpura on the lower extremities and gluteal area. Investigations revealed leukocytosis, neutrophilia, a high neutrophils/lymphocytes ratio, high Erythrocyte Sedimentation Rate, proteinuria, and a positive occult blood test. Inpatient therapy consisted of intravenous corticosteroids, intravenous Histamin-2 (H2) blockers, and oral nonsteroidal anti-inflammatory drugs. Upon discharge, all therapy was administered orally, with corticosteroids gradually tapered over 14 days. The patient showed clinical improvement without complications. Conclusion: HSP should be considered in the differential diagnosis of recurrent abdominal pain, even when of purpura and joint symptoms are absent initially. Early recognition can prevent diagnostic delays and reduce the risk of serious complications.

Background: Kawasaki disease (KD) is an acute vasculitis of childhood that usually affects children under five but can also present in adolescence. Although less common, adolescent cases pose unique diagnostic and therapeutic challenges due to atypical features and increased cardiovascular risk. Methods: A targeted PubMed search, supplemented by a Google Scholar screening, was conducted to identify studies on KD in adolescents published between 2000 and 2024. Nine studies were included in the synthesis, along with one national surveillance study. This scoping review was conducted in accordance with the PRISMA-Scr guidelines. Results: Adolescents with KD often do not meet full diagnostic criteria, leading to delays or missed diagnoses. Presentations frequently involve symptoms that mimic those of mucocutaneous, gastrointestinal, musculoskeletal, and neurological conditions. These delays are linked with higher rates of coronary artery abnormalities compared with younger children. Intravenous immunoglobulin (IVIG) remains the primary treatment, though resistance occurs more frequently in this group. Beyond the acute illness, adolescent KD impacts school participation, physical activity, and independence, underscoring the importance of addressing developmental and psychosocial outcomes. Conclusions: While KD is primarily a disease of younger children, adolescent cases require greater clinical awareness, prompt intervention, and developmentally informed follow-up to reduce complications and support effective transition to adult care.

Fatal rupture of a giant left coronary artery aneurysm in an infant with Kawasaki disease. A case report with systematic literature review.

BackgroundImmunoglobulin A vasculitis (IgAV) is the most common childhood vasculitis and can lead to immunoglobulin A vasculitis nephritis (IgAVN) in severe cases, potentially progressing to kidney failure in a subset of children. Safer and more effective treatments are needed to improve outcomes in these children. This study aimed to evaluate the efficacy and safety of telitacicept in the treatment of children with IgAV and IgAVN.MethodsThis is a single-center, retrospective observational study of twenty four children with IgAV or IgAVN who received telitacicept treatment, and thirty matched children with IgAVN who only received conventional treatment were taken as the control group for children with IgAVN who received telitacicept treatment in acute phase. The treatment response was evaluated through urine protein, serum albumin, eGFR and serum immunoglobulin levels, and data was analyzed at telitacicept initiation and at 4, 12, 24 and 36 weeks after treatment.ResultsA total of twenty four children (thirteen boys and eleven girls) with IgAV (n = 5) and IgAVN (n = 19, comprising ten acute and nine chronic cases) were enrolled. All children with IgAV experienced improvement of skin, joint, and gastrointestinal symptoms after telitacicept treatment, with no kidney involvement during follow-up. In children with IgAVN, the urinary protein-to-creatinine ratio (UPCR) significantly decreased at 36 weeks compared to baseline (P < 0.05) in both acute and chronic groups, while estimated glomerular filtration rate (eGFR) remained stable (P > 0.05). In addition, the dose of steroids administered during the treatment with telitacicept was significantly reduced, the acute IgAVN group exhibited significantly greater steroid reduction between weeks 4 and 24 compared with the controls group (P < 0.05). Furthermore, serum immunoglobulin levels (IgA, IgG) significantly decreased 12 weeks after telitacicept treatment (P < 0.01), and no other adverse reactions observed.ConclusionTelitacicept appears to be a promising therapy for children with IgAV and IgAVN, effectively inducing proteinuria remission, improving systemic symptoms, and reducing the use of steroids, with favorable safety.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12969-025-01159-3.

Immunoglobulin A vasculitis (IgAV) is the most common cause of systemic vasculitis in childhood. Due to the continued use of the disease name "anaphylactoid purpura" in China, several misunderstandings have arisen in clinical practice and treatment regimens differ widely. In addition, new research and evidence-based data have grown. The Subspecialty Group of Immunology, Society of Pediatrics, Chinese Medical Association and the Chinese Alliance of Pediatric Rheumatic and Immunologic Diseases initiated an update of guidelines for the diagnosis and management of childhood IgAV. The aim therefore was to provide agreed consensus recommendations for diagnosis and treatment for children with IgAV. This study utilized the Delphi technique to develop an evidence-based expert consensus for childhood IgAV. We conducted a systematic literature review to retrieve evidence, which was graded using GRADE (Grading of Recommendations Assessment, Development, and Evaluation) criteria. Two rounds of Delphi voting and a consensus meeting involving 23 experts were conducted. Recommendations were accepted when ≥ 75% of experts agreed. In total, five recommendations for diagnosis, six for treatment, one for prognosis, and two for health education for pediatric IgAV were accepted. Diagnostic recommendations included the use of the European Alliance of Associations for Rheumatology/Pediatric Rheumatology International Trials Organization/Pediatric Rheumatology European Society-endorsed Ankara 2008 classification criteria for IgAV diagnosis. In addition, appropriate use of imaging, gastrointestinal endoscopy, skin biopsy, and kidney biopsy are recommended. Kidney biopsy is recommended for children with IgAV presenting with nephrotic syndrome/nephrotic-range proteinuria, reduced estimated glomerular filtration rate, acute nephritis syndrome, or persistent moderated/mild proteinuria. Treatment recommendations involved indications for glucocorticoid use, immunosuppressant use, and intravenous immunoglobulin use. It also addressed the inappropriate use of prophylactic glucocorticoid treatment and recommended against routine employment of plasmapheresis. Health education placed emphasis on the inappropriate use of anti-anaphylactic treatment and proffers dietary suggestions. This guideline provides evidence-based recommendations for the diagnosis and management of IgAV in children. This will facilitate improved and standardized care.

IgA vasculitis is the most common vasculitis in childhood, and its main feature is leukocytoclastic vasculitis, in which the capillaries are affected by the deposit of IgA immune complexes. Skin rash is the principal clinical manifestation, along with arthralgia or arthritis, digestive and renal tract involvement, and is often self-limiting. Although it occurs at any age, it prefers children between 3 and 12 years. It is common to identify a trigger, the most frequently associated with infection, with reports of up to 31% along respiratory tract infections, followed by gastrointestinal infections at 5%. Dermatological manifestations are the characteristic element of the disease; 100% of patients have purpura at some point; however, renal involvement determines the prognosis of these patients. The diagnosis is clinical, supported by laboratory and cabinet assistants and classification criteria; however, since the prognosis is mainly conditioned by renal involvement, having simple and safe alternatives, adequate follow-up, evaluation of the efficacy of the treatment, and the prognosis of the disease are some of the main objectives of biomarkers. Initial treatment consists of general measures, but in the case of gastrointestinal, renal, or other target organ involvement, such as testicles, therapy with corticosteroids and immunosuppressants is necessary. Since the end of the last century, it has been recognized that not all patients with IgA vasculitis had a benign outcome; however, recent data supports a deleterious outcome both in patients with nephritis and in pregnancy.

Objective: Kawasaki disease (KD) is an acute systemic vasculitis of childhood that may lead to coronary artery involvement (CAI) if not promptly treated. Early identification of laboratory predictors for coronary complications is essential. This study aimed to identify early laboratory predictors of coronary complications in KD, to help clinicians assess risk during the acute phase. Material and Methods: We retrospectively analyzed 38 pediatric KD patients. Clinical and laboratory data—including hemoglobin (Hb), hematocrit (Htc), white blood cell count (WBC), platelet counts (PLT), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), liver enzymes, and Harada scores—were collected and compared between patients with and without CAI. Receiver operating characteristic (ROC) and logistic regression analyses were performed. Results: The mean age was 35.0±32.6 months, with 65.8% male. CAI was observed in 16 of 38 patients (42.1%). No statistically significant differences were found in the laboratory values at diagnosis between patients with and without CAI. Conclusion: Routine hematological and inflammatory markers at admission were not predictive of CAI in KD. These findings highlight the need for high clinical suspicion in incomplete cases and suggest that incorporating clinical features and risk scores may improve early risk stratification.

Kawasaki disease (KD) is the most common childhood vasculitis. Approximately 25% of KD patients are refractory to standard intravenous immunoglobulin (IVIG) therapy and frequently develop coronary artery lesions (CAL) that result in long-term complications. Transcriptome studies utilizing blood cells from KD patients and reported animal model studies had identified interleukin (IL)-1β as a crucial component of an essential immune pathway in the formation of CAL. We previously reported that high-dose immunoglobulin G (IgG) treatment completely inhibited tumor necrosis factor (TNF)-α-stimulated inflammatory responses in an in vitro human coronary artery endothelial cells (HCAECs) model. Here, we show that IL-1β, but not TNF-α, stimulation markedly induced nuclear protein expression of NF-kappa-B inhibitor zeta (IκBζ) in HCAECs. It is of particular significance that IL-1β-induced IκBζ expression is entirely refractory to high-dose IgG treatment. Therefore, IκBζ may be a critical factor in the IVIG-resistant vascular inflammatory responses in severe KD. Itaconate is a Krebs cycle-derived metabolite with several immunomodulatory effects. Dimethyl itaconate (DI), a membrane-permeable derivative of itaconate, can significantly suppress IL-1β-induced IκBζ expression in HCAECs. DI is an analog of dimethyl fumarate (DMF), which is already in clinical use for some diseases. Like DI, DMF suppressed IL-1β-induced IκBζ expression and subsequent production of inflammatory cytokines, including IL-6 and G-CSF. This study identified IκBζ as an essential inflammatory factor in IVIG-resistant inflammatory responses in HCAECs. Immunomodulatory substances, such as DI and/or DMF, may be therapeutically exploited as a novel drug to alleviate inflammation in severe IVIG-resistant KD patients.

Takayasu arteritis is the most common large-vessel vasculitis in childhood, but there is a lack of literature regarding childhood-onset Takayasu arteritis (c-TAK) in Southeast Asia. We aim to describe a c-TAK cohort in Singapore and highlight a unique subset that first presents with Kawasaki-like disease (KD). A single-centre cohort study in Singapore of consecutive children diagnosed with c-TAK between 2002 and 2023 was performed. Demographic and clinical features, laboratory and angiographic findings, treatment, and outcomes were summarised. Disease activity was evaluated using the Paediatric Vasculitis Disease Activity Score and inflammatory markers. Twenty-three patients, fulfilling both the EULAR/ PRINTO/PReS and ACR/EULAR 2022 criteria, were recruited. The most common clinical features at diagnosis were fever (15, 65%) and neurological symptoms (11, 48%, half of which presented with stroke), while the most prevalent angiographic pattern by Hata's classification was Type V (21, 91%). Eight children (35%) initially presented with refractory KD, and these patients were significantly younger, more male-predominant, and had higher inflammatory markers at diagnosis; all of them had coronary artery involvement, but none had intracranial vascular findings. Of the entire cohort, 16 (70%) achieved inactive disease on medications with a median duration of 6 months (interquartile range [IQR]: 4-11), and 8 (35%) achieved remission off medications with a median duration of 43 months (IQR 35-60). Our c-TAK cohort has high proportions of neurological involvement and stroke. This is also the first cohort study to describe a distinct group of patients who first presented with refractory KD.

Takayasu arteritis (TAK) is a rare, chronic large-vessel vasculitis that primarily affects young females. Neurological and cardiac involvement in paediatric TAK is uncommon, and their concurrent occurrence is even rarer. We report a unique case of TAK in a girl in middle childhood who presented with progressive abdominal distension, right-sided hemiparesis, right upper limb dystonia and right-sided upper motor neuron (UMN) facial palsy. Over the preceding 6 months, she experienced recurrent episodes of cough, dyspnoea, lower limb pain and abdominal discomfort. Examination revealed cold extremities, markedly diminished lower limb pulses and relatively preserved upper limb pulses. Measurement of blood pressure in all 4 limbs demonstrated significant discrepancies. Imaging studies revealed severe stenosis of the lower thoracic aorta on CT angiography, a large left ventricular thrombus with global hypokinesia on echocardiography and basal ganglia infarction on brain MRI. A diagnosis of TAK was established based on the European Alliance of Associations for Rheumatology (EULAR) criteria, with an Indian Takayasu Clinical Activity Score 2010 (ITAS 2010) of 16. Treatment included corticosteroids, low molecular weight (LMW) heparin, enalapril, aspirin and warfarin. The patient demonstrated marked clinical improvement, including complete resolution of dystonia and facial palsy, along with normalisation of cardiac function at follow-up. This case highlights an unusual presentation of paediatric TAK with concurrent stroke, heart failure and a large left ventricular thrombus. To the best of our knowledge, dystonia as a presenting feature of cerebral ischaemia in paediatric TAK has not been previously reported. This case underscores the importance of early recognition and management of atypical neurovascular features in childhood vasculitis.

Superior Mesenteric Artery (SMA) syndrome is an uncommon gastrointestinal blockage caused by the compression of the third section of the duodenum between the abdominal aorta and the superior mesenteric artery. Henoch Schönlein Purpura (HSP), or IgA vasculitis, is the most common childhood vasculitis, marked by palpable purpura, arthralgia, gastrointestinal symptoms and renal involvement. The coexistence of both conditions is exceptionally rare. We report a 13-year-old girl who presented with persistent epigastric pain and bilious vomiting, followed by cutaneous purpura and mild hematuria. Imaging and histopathology confirmed SMA syndrome and HSP respectively. Management with nutritional support and corticosteroids led to complete resolution. This case underscores the importance of recognizing dual pathologies and the role of steroids in treating SMA syndrome secondary to HSP.

IgA vasculitis (IgAV) and Kawasaki disease (KD) are the most common forms of childhood vasculitis. Although various factors such as viral infections, genetic factors, and environmental factors are involved in the development of both diseases, their pathogenesis remains unclear. The interferon (IFN) signature, which reflects the activation of type I IFN signaling pathways, is a diagnostic and prognostic tool that contributes significantly to the pathogenesis and management of autoimmune diseases. In our study, we aimed to investigate the role of the IFN signature in patients with IgAV and KD. Thirty-two children with IgAV and four patients diagnosed with KD were included in the study. Serum levels of IL-1, IL-6, IL-8, IL-10, IL-17, IL-18, TNF-α, TNF-R1, TNF-R2, and IFN-gamma were analyzed in the serum samples of all participants, and the expression of IFN-related genes (STAT1, IFI27, IFI44, IFI44L, IFIT1, and RSAD2) was assessed in the patients and healthy controls (n = 26) to calculate the IFN score by RT-PCR method. A significant increase in the expression of three genes (IFIT1, IFI44, and IFI27) and decreased expression of the other three genes (RSAD2, STAT1, and IFI44L) was found in patients with IgAV and KD compared to the control group. Significantly higher IFN scores (IFN > 3) were found in patients with gastrointestinal involvement, in patients who required corticosteroid therapy, and in patients who had to be hospitalized. No significant difference in IFN levels was found between patients with and without renal involvement. Significantly higher serum IL-1 levels were found in patients with gastrointestinal symptoms with IgAV. High IFN scores were found in three out of four patients diagnosed with KD. A dysregulated type 1 IFN signature was found in patients with IgAV and KD compared to the control group. A significantly increased risk of gastrointestinal involvement required corticosteroid therapy, and hospitalization was observed in patients diagnosed with IgAV who had high IFN levels. This underlines the idea that the IFN score could serve as a crucial prognostic indicator.

Henoch-Schönlein purpura (HSP), synonymous with the recent term immunoglobulin A vasculitis (IgAV), is an acute autoimmune IgA-mediated disorder classified under the group of small-vessel vasculitis (SVV). It clinically manifests with the pathognomonic tetrad of palpable purpura, abdominal pain, hematuria or proteinuria, and arthritis. Although the full spectrum of clinical features is not invariably present and additional clinical manifestations may be seen, cutaneous manifestations are observed in 100% of cases, thereby serving as the one most definitive diagnostic criterion. Young children, predominantly between ages of 2 and 10, are generally affected by the disease (90% of the cases), thereby establishing it as the most common vasculitis of childhood. We describe a case of two episodes of Chlamydia pneumoniae induced HSP in an 8-year-old boy with an acute onset of a rash and an upper respiratory tract infection preceding the onset, and with possible simultaneous multi-factorial infective etiology contributing to the severity of the disease. Given the rarity of reported cases, only two to our knowledge, it is challenging to establish a definitive causal relationship between Chlamydia pneumoniae and HSP. However, this uncommon association highlights the importance of considering this atypical pathogen in the etiological differential diagnosis of HSP, especially in patients presenting with preceding respiratory symptoms. Early diagnosis is crucial for preventing complications and ensuring optimal management, with prompt recognition of diverse triggers, such as infections, being essential for tailored therapy and improved patient outcomes.

Kawasaki disease (KD) is an acute childhood vasculitis, commonly seen in children under the age of five. Despite extensive research over the past five decades, the pathogenesis of KD remains elusive. The objective of this epigenetic reanalysis study is to delineate common pathways involved in KD using a bioinformatics approach. Array datasets from the Gene Expression Omnibus repository were extracted and subjected to analysis using the Chip Analysis Methylation Pipeline in the R statistical tool for the identification of differential methylation probes and differential methylation regions. Adaptive immune genes CD8B, RAG1, IL-7R, STAT1, and CCR7 were significantly hypermethylated in acute KD as compared to healthy controls. Gene enrichment analysis showed that genes involved in T-cell receptor activation and differentiation, antigen processing and presentation of MHC class I were hypermethylated, whereas neutrophil degranulation was hypomethylated in the acute phase of KD as compared to healthy controls. The proportion of neutrophils significantly increased, while the proportions of CD4 T-cells and CD8 T-cells decreased in the peripheral blood of children with acute KD as compared to healthy controls. Reduced proportions of CD4 T cells and CD8 T cells, as well as hypermethylation of their genes, have been observed in the peripheral blood of patients with acute KD.