Disease flares with baricitinib dose reductions and development of flare criteria in patients with CANDLE/PRAAS.

OBJECTIVES: Patients with chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature/proteasome-associated autoinflammatory syndrome (CANDLE/PRAAS) respond to the janus kinase inhibitor 1/2 inhibition with baricitinib at exposures higher than in rheumatoid arthritis. Baricitinib dose reductions to minimise exposure triggered disease flares which we used to develop 'flare criteria'. METHODS: Of 10 patients with CANDLE/PRAAS treated with baricitinib in an open-label expanded-access programme, baricitinib doses were reduced 14 times in 9 patients between April 2014 and December 2019. Retrospective data analysis of daily diary scores and laboratory markers collected before and after the dose reductions were used to develop 'clinical' and 'subclinical' flare criteria. Disease flare rates were compared among patients with <25% and >25% dose reductions and during study visits when patients received recommended 'optimized' baricitinib doses (high-dose visits) versus lower than recommended baricitinib doses (low-dose visits) using two-sided χ2 tests. RESULTS: In the 9/10 patients with CANDLE with dose reduction, 7/14 (50%) times the dose was reduced resulted in a disease flare. All four dose reductions of >25% triggered a disease flare (p <0.05). Assessment of clinical and laboratory changes during disease flares allowed the development of disease flare criteria that were assessed during visits when patients received high or low doses of baricitinib. Disease flare criteria were reached during 43.14% of low-dose visits compared with 12.75% of high-dose visits (p <0.0001). Addition of an interferon score as an additional flare criterion increased the sensitivity to detect disease flares. CONCLUSION: We observed disease flares and rebound inflammation with baricitinib dose reductions and proposed flare criteria that can assist in monitoring disease activity and in designing clinical studies in CANDLE/PRAAS.

Platelet count and risk of severe illness in hospitalised children with Influenza-Like illness.

AIM: To examine the clinical significance of thrombocytosis (platelets > 500 × 109 /L) in admitted children with an influenza-like illness. METHODS: We performed a database analysis consisting of patients evaluated at our medical centers with an influenza-like illness between 2009 and 2013. We included paediatric patients and examined the association between platelet count, respiratory viral infections, and admission outcomes (hospital length of stay and admission to the paediatric intensive care unit) using regression models adjusting for multiple variables. RESULTS: A total of 5171 children were included in the study cohort (median age 0.8 years; interquartile range, 0.2-1.8; 58% male). Younger age, and not the type of viral infection, was associated with a high platelet count (p < 0.001). Elevated platelet count independently predicted admission outcomes (p ≤ 0.05). The presence of thrombocytosis was associated with an increased risk for a prolonged length of stay (odds ratio = 1.2; 95% Confidence interval = 1.1 to 1.4; p = 0.003) and admission to the paediatric intensive care unit (odds ratio = 1.5; 95% Confidence interval = 1.1 to 2.0; p = 0.002). CONCLUSION: In children admitted with an influenza-like illness, a high platelet count is an independent predictor of admission outcomes. Platelet count may be used to improve risk assessment and management decisions in these paediatric patients.

Evaluation and Management of Deficiency of Adenosine Deaminase 2: An International Consensus Statement.

Importance: Deficiency of adenosine deaminase 2 (DADA2) is a recessively inherited disease characterized by systemic vasculitis, early-onset stroke, bone marrow failure, and/or immunodeficiency affecting both children and adults. DADA2 is among the more common monogenic autoinflammatory diseases, with an estimate of more than 35 000 cases worldwide, but currently, there are no guidelines for diagnostic evaluation or management. Objective: To review the available evidence and develop multidisciplinary consensus statements for the evaluation and management of DADA2. Evidence Review: The DADA2 Consensus Committee developed research questions based on data collected from the International Meetings on DADA2 organized by the DADA2 Foundation in 2016, 2018, and 2020. A comprehensive literature review was performed for articles published prior to 2022. Thirty-two consensus statements were generated using a modified Delphi process, and evidence was graded using the Oxford Center for Evidence-Based Medicine Levels of Evidence. Findings: The DADA2 Consensus Committee, comprising 3 patient representatives and 35 international experts from 18 countries, developed consensus statements for (1) diagnostic testing, (2) screening, (3) clinical and laboratory evaluation, and (4) management of DADA2 based on disease phenotype. Additional consensus statements related to the evaluation and treatment of individuals with DADA2 who are presymptomatic and carriers were generated. Areas with insufficient evidence were identified, and questions for future research were outlined. Conclusions and Relevance: DADA2 is a potentially fatal disease that requires early diagnosis and treatment. By summarizing key evidence and expert opinions, these consensus statements provide a framework to facilitate diagnostic evaluation and management of DADA2.

Pediatric respiratory admissions and related viral infections during the COVID-19 pandemic.

INTRODUCTION: The COVID-19 pandemic has affected the incidence of respiratory viral infections. Our aim was to assess changes in pediatric admissions due to respiratory diseases and associated respiratory viral infections. METHODS: An observational study including all respiratory admissions to the pediatric departments from January 2015 to August 2021. We compared respiratory admission percentage, respiratory viral panel results and clinical characteristics of these admissions between two study periods, January 2015 to February 2020 (pre-COVID-19 era) and March 2020 to August 2021 (COVID-19 era). RESULTS: A total of 8774 respiratory admissions were included, 7157 pre-COVID-19 era and 1617 COVID-19 era. Relative to all pediatric admissions, there was a 17% decrease in respiratory admission percentage during the COVID-19 era (p < 0.001) and a 31% and 22% decreased in the admission percentages due to bronchiolitis (p < 0.001) and pneumonia (p < 0.001), respectively. However, admission percentages for asthma, wheezing illness, complicated pneumonia, and stridor remained the same. There was a significant decrease in the detection of a respiratory viral pathogen associated with these respiratory admissions (p < 0.001). This was related to a significant decrease in the detection of respiratory syncytial virus (RSV) (37% vs. 27%, p < 0.001) and influenza (5% vs. 0.3%, p < 0.001), but not other respiratory viruses. An alteration in the circulation pattern of most respiratory viruses, was observed. CONCLUSIONS: During the COVID-19 pandemic, a decrease in the prevalence of RSV and influenza was associated with a significant decrease in admissions for bronchiolitis and pediatric pneumonia. This may allow us to estimate the significance of preventive measures for RSV and influenza on pediatric respiratory admissions.

Multisystem inflammatory syndrome in children associated with COVID-19 presenting as cervical inflammation.

AIM: The major clinical manifestations multisystem inflammatory syndrome in children (MIS-C) are fever, gastrointestinal and cardiac. The aim of this study was to describe MIS-C in a series of patients who presented primarily with cervical manifestations. METHODS: We retrospectively reviewed medical records of all patients who met the Centers for Disease Control and Prevention and World Health Organization MIS-C diagnostic criteria treated at Hadassah-Hebrew University Medical Center between April 2020 and September 2021. RESULTS: Of 37 children diagnosed with MIS-C (median age: 10.2 years, range 1.5-18 years, 20 male) five, 13.5% (median age: 14.4 years, range 9.2-17.5 years) presented with cervical symptoms mimicking neck infections. One was hospitalised with a working diagnosis of retropharyngeal abscess, and four with acute cervical lymphadenitis that did not respond to early antibiotic treatment. All developed full MIS-C phenotype. CONCLUSION: MIS-C may present as cervical inflammation. An ill-appearing child with symptoms and/or signs of cervical inflammation should be evaluated for clinical and laboratory features of MIS-C, thereby facilitating prompt treatment of this potentially fatal disorder.

Obstacles in Early Diagnosis of Children With Juvenile Idiopathic Arthritis: A Nationwide Israeli Retrospective Study.

OBJECTIVE: Characterization of the stages that patients with juvenile idiopathic arthritis (JIA) pass until they are diagnosed, and analysis of the different causes that lead to a delay in JIA diagnosis in Israel. METHODS: This is a retrospective cohort study conducted in 8 pediatric rheumatology centers in Israel. All patients diagnosed with JIA between October 2017 and October 2019 were included in the study. Demographic, clinical, and data regarding the referring physicians were collected from hospital and community medical charts. RESULTS: Of 207 patients included in the study, 201 cases were analyzed, 71.1% of the population were female. Patients, on average, were evaluated during the diagnostic process by 3.1 different physicians. In most cases, they initially met with a pediatrician in the community setting (61.2%), and later, most commonly referred to a rheumatologist by the community pediatrician (27.9%). The median time until diagnosis was 56.0 days (range: 1.0-2451.0 days). Patients diagnosed with polyarticular and spondyloarthritis/enthesitis-related arthritis (SpA/ERA) JIA subtypes had the longest period until diagnosis (median: 115.5 and 112.0 days, respectively). Younger age correlated with a quicker diagnosis, and females were diagnosed earlier compared to males. Fever at presentation significantly shortened the time to diagnosis (P < 0.01), whereas involvement of the small joints/sacroiliac joints significantly lengthened the time (P < 0.05). CONCLUSION: This is the first nationwide multicenter study that analyzes obstacles in the diagnosis of JIA in Israel. Raising awareness about JIA, especially for patients with SpA/ERA, is crucial in order to avoid delays in diagnosis and treatment.

Risk factors for haemodynamic compromise in multisystem inflammatory syndrome in children: a multicentre retrospective study.

OBJECTIVES: To identify predictors of a severe clinical course of multisystem inflammatory syndrome in children (MIS-C), as defined by the need for inotropic support. METHODS: This retrospective study included patients diagnosed with MIS-C (according to the CDC definition) in nine Israeli and one US medical centre between July 2020 and March 2021. Univariate and multivariate regression models assessed odds ratio (OR) of demographic, clinical, laboratory and imaging variables during admission and hospitalization for severe disease. RESULTS: Of 100 patients, 61 (61%) were male; mean age 9.65 (4.48) years. Sixty-five patients were hypotensive, 44 required inotropic support. Eleven patients with MIS-C fulfilled Kawasaki disease diagnostic criteria; 87 had gastrointestinal symptoms on admission. Echocardiographic evaluation showed 10 patients with acute coronary ectasia or aneurysm, and 37 with left ventricular dysfunction. In a univariate model, left ventricular dysfunction was associated with severe disease [OR 4.178 (95% CI 1.760, 9.917)], while conjunctivitis [OR 0.403 (95% CI 0.173, 0.938)] and mucosal changes [OR 0.333 (95% CI 0.119, 0.931)] at admission were protective. Laboratory markers for a severe disease course were low values of haemoglobin, platelets, albumin and potassium; and high leukocytes, neutrophils, troponin and brain natriuretic peptide. In multivariate analysis, central nervous system involvement and fever >39.5°C were associated with severe disease. Mucosal involvement showed 6.2-fold lower risk for severe disease. Low haemoglobin and platelet count, and elevated C-reactive protein and troponin levels were identified as risk factors for severe disease. CONCLUSION: Key clinical and laboratory parameters of MIS-C were identified as risk factors for severe disease, predominantly during the disease course and not at the time of admission; and may prompt close monitoring, and earlier, more aggressive treatment decisions. Patients presenting with a Kawasaki-like phenotype were less likely to require inotropic support.

Case Series of Myocarditis Following mRNA COVID Vaccine Compared to Pediatric Multisystem Inflammatory Syndrome: Multicenter Retrospective Study.

INTRODUCTION: Since the development of COVID-19 vaccines, more than 4.8 billion people have been immunized worldwide. Soon after vaccinations were initiated, reports on cases of myocarditis following the second vaccine dose emerged. This study aimed to report our experience with adolescent and young adults who developed post-COVID-19 vaccine myocarditis and to compare these patients to a cohort of patients who acquired pediatric inflammatory multisystem syndrome (PIMS/PIMS-TS) post-COVID-19 infection. METHODS: We collected reported cases of patients who developed myocarditis following COVID-19 vaccination (Pfizer mRNA BNT162b2) from all pediatric rheumatology centers in Israel and compared them to a cohort of patients with PIMS. RESULTS: Nine patients with post-vaccination myocarditis were identified and compared to 78 patients diagnosed with PIMS. All patients with post-vaccination myocarditis were males who developed symptoms following their second dose of the vaccine. Patients with post-vaccination myocarditis had a shorter duration of stay in the hospital (mean 4.4 ± 1.9 vs. 8.7 ± 4.7 days) and less myocardial dysfunction (11.1% vs. 61.5%), and all had excellent outcomes as compared to the chronic changes among 9.2% of the patients with PIMS. CONCLUSION: The clinical course of vaccine-associated myocarditis appears favorable, with resolution of the symptoms in all the patients in our cohort.

Outcomes of SARS-CoV-2 infection among children and young people with pre-existing rheumatic and musculoskeletal diseases.

OBJECTIVES: Some adults with rheumatic and musculoskeletal diseases (RMDs) are at increased risk of COVID-19-related death. Excluding post-COVID-19 multisystem inflammatory syndrome of children, children and young people (CYP) are overall less prone to severe COVID-19 and most experience a mild or asymptomatic course. However, it is unknown if CYP with RMDs are more likely to have more severe COVID-19. This analysis aims to describe outcomes among CYP with underlying RMDs with COVID-19. METHODS: Using the European Alliance of Associations for Rheumatology COVID-19 Registry, the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Registry, and the CARRA-sponsored COVID-19 Global Paediatric Rheumatology Database, we obtained data on CYP with RMDs who reported SARS-CoV-2 infection (presumptive or confirmed). Patient characteristics and illness severity were described, and factors associated with COVID-19 hospitalisation were investigated. RESULTS: 607 CYP with RMDs <19 years old from 25 different countries with SARS-CoV-2 infection were included, the majority with juvenile idiopathic arthritis (JIA; n=378; 62%). Forty-three (7%) patients were hospitalised; three of these patients died. Compared with JIA, diagnosis of systemic lupus erythematosus, mixed connective tissue disease, vasculitis, or other RMD (OR 4.3; 95% CI 1.7 to 11) or autoinflammatory syndrome (OR 3.0; 95% CI 1.1 to 8.6) was associated with hospitalisation, as was obesity (OR 4.0; 95% CI 1.3 to 12). CONCLUSIONS: This is the most significant investigation to date of COVID-19 in CYP with RMDs. It is important to note that the majority of CYP were not hospitalised, although those with severe systemic RMDs and obesity were more likely to be hospitalised.

Neurological and neurodevelopmental symptoms in children with familial Mediterranean fever and their siblings.

Familial Mediterranean fever is a common autoinflammatory disease characterized by periodic attacks of fever and serositis. There are few reports describing neurological symptoms in patients with FMF. The aim of this study was to systematically assess the neurologic and developmental involvement in pediatric patients with FMF. Between the years 2016 and 2019, parents of children with FMF were asked to complete a questionnaire regarding the presence of neurological and developmental symptoms in their children with and without FMF. Demographic data, clinical characteristics, and disease course of FMF patients were collected from the medical charts. Neurodevelopmental manifestations were compared between the children with FMF and their siblings. A total of 205 children were enrolled (11.6 ± 4.7 years of age): 111 children with FMF and 94 healthy siblings in the control group. Neurological morbidity was frequently reported in children with FMF: 44 (40%) had recurrent headaches, 31 (28%) ADHD symptoms, 27 (24%) learning disabilities, and 10 (9%) febrile convulsions. Headaches and febrile convulsions were significantly more prevalent in children with FMF as compared to their siblings (ps < 0.05). ADHD and learning disabilities were associated with poor adherence to colchicine treatment.Conslusions: The present study found an increased prevalence of ADHD, learning disabilities, headaches, and febrile seizures in children with FMF. The findings underscore the importance of addressing the neurodevelopmental domain in children with FMF. In addition, detection and treatment of ADHD and learning disabilities could improve adherence with therapy and control of the underlying disease. What is Known: • Familial Mediterranean fever (FMF) is the most common inherited auto-inflammatory disease, characterized by recurrent attacks of fever, serositis, and arthritis. • Some previous case reports also described rare neurological manifestations in children with FMF. What is New: • The study found an increased prevalence of headaches, febrile seizures, ADHD, and learning disabilities, in children with FMF. • The findings underscore the importance of addressing the neurological domain in this population, which could potentially improve adherence with therapy and control of the underlying disease.

Increased prevalence of attention-deficit hyperactivity disorder symptomatology in patients with familial Mediterranean fever.

OBJECTIVES: Previous studies suggest that exposure to inflammation in infancy may increase the risk for attention-deficit and hyperactivity disorder (ADHD). We studied the ADHD manifestations among 124 familial Mediterranean fever (FMF) patients and examined the relationship between FMF patient characteristics and ADHD. METHODS: Clinical, demographic, and genetic data were abstracted from patients' medical records and supplemented by information obtained during clinic visits. ADHD manifestations were assessed using the Diagnostic and Statistical Manual of Mental Disorders (5th ed.) questionnaire. RESULTS: ADHD was diagnosed in 42 (32.8%) FMF patients, a rate significantly higher than in unselected populations (∼8%). A majority (n = 27, 64.3%) had combined inattentive, hyperactive-impulsive manifestations. Eight (19%) had predominantly hyperactive-impulsive, and seven (16.6%) had predominantly inattentive symptoms. FMF patients with severe manifestations reported more ADHD symptoms. FMF patients with ADHD symptoms were less adherent to their treatment regimen, with only 61.9% of the patients with ADHD symptoms adhering to colchicine therapy compared to 92.7% of the patients without ADHD symptoms. CONCLUSION: The high prevalence of ADHD characteristics in children with FMF may support the neuroimmune hypothesis that chronic inflammation increases the risk for ADHD. Children with FMF should be screened for ADHD as its presence may adversely affect adherence to treatment.

Discontinuation of Colchicine Therapy in Children With Familial Mediterranean Fever.

OBJECTIVE: Colchicine has been considered a lifelong therapy for familial Mediterranean fever (FMF). Recent studies describe patients who discontinued colchicine, but there is a lack of data pertaining to predictors of success. The aims of our study were to describe a cohort of pediatric patients with FMF who discontinued colchicine therapy, and to identify factors predicting successful termination of colchicine. METHODS: This study describes a cohort of pediatric patients with FMF who discontinued colchicine therapy following a relatively prolonged attack-free period (> 6 months), and identifies factors predicting successful termination. Data collected included demographic, clinical, and laboratory characteristics of children diagnosed with FMF aged < 16 years who underwent a trial of colchicine discontinuation. Data from patients who successfully ceased colchicine therapy were compared to those of patients who relapsed. RESULTS: Of 571 patients with FMF, 59 (10.3%) discontinued colchicine therapy. The average attack-free period before enrollment was 0.97 ± 1.4 years. Follow-up after ceasing colchicine was 5.0 ± 3.05 years, during which time 11 (20%) patients had an attack. The most common symptoms were fever (100%) and abdominal pain (80%). For those failing discontinuation, colchicine was restarted within 1.3 years (range 0.3-5.0, median 0.7 yrs). A longer attack-free period prior to colchicine discontinuation predicted success. Myalgia and arthritis prior to colchicine cessation were more common among children who required renewal of colchicine. CONCLUSION: Cessation of colchicine therapy should be considered following prolonged remission in a select group of patients. Patients with arthritis or myalgia are more likely to have an attack after ceasing colchicine therapy.

Hijab Pin Ingestions.

OBJECTIVES: To characterize the clinical manifestations, outcomes, and complications of hijab pin ingestion in adolescents and to identify risk factors for a need for intervention. METHODS: A retrospective review of patients <25 years of age who presented to our emergency department because of hijab pin ingestion between 2007 and 2018. Comparison was performed between impaled and nonimpaled pins. RESULTS: We reviewed 1558 foreign-body ingestion cases. Of these, 208 (13.3%) patients presented because of hijab pin ingestion, with a total of 225 ingested pins. The mean patient age was 14.7 ± 4.1 years, and 88% of patients were girls. Time from ingestion to presentation was 24 ± 49.5 hours. Most pins were located in the stomach (46.6%), and 18.6% of all pins were impaled. Location in the stomach (odds ratio = 4.3 [95% confidence interval: 1.9-9.2]; P < .001) and abdominal tenderness on examination (odds ratio = 2.7 [95% confidence interval: 1.3-5.6]; P = .007) were strong independent risk factors for an impaled pin. Time to intervention was 22.9 hours, and 41 endoscopies were performed. One patient required laparoscopic surgery. No complications were observed. CONCLUSIONS: The hijab pin is an increasingly encountered foreign body in pediatric practice. Its specific clinical features distinguish it from other sharp objects. A delayed interventional approach in selected patients does not carry a higher risk of complications and results in significantly fewer interventions compared to existing guidelines. These findings will help guide pediatric specialists in this prevalent clinical scenario. Management recommendations are proposed.

Minor Clinical Impact of COVID-19 Pandemic on Patients With Primary Immunodeficiency in Israel.

In the last few months the world has witnessed a global pandemic due to severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection causing coronavirus disease 2019 (COVID-19). Obviously, this pandemic affected individuals differently, with a significant impact on populations considered to be at high-risk. One such population, was assumed to be patients with primary genetic defect involving components or pathways of the immune system. While human immunity against COVID-19 is not fully understood, it is, so far, well documented, that both adaptive and innate cells have a critical role in protection against SARS-CoV-2. Here, we aimed to summarize the clinical and laboratory data on primary immunodeficiency (PID) patients in Israel, who were tested positive for SARS-CoV-2, in order to estimate the impact of COVID-19 on such patients. Data was collected from mid-February to end-September. During this time Israel experienced two "waves" of COVID-19 diseases; the first, from mid-February to mid-May and the second from mid-June and still ongoing at the end of data collection. A total of 20 PID patients, aged 4 months to 60 years, were tested positive for SARS-CoV-2, all but one, were detected during the second wave. Fourteen of the patients were on routine monthly IVIG replacement therapy at the time of virus detection. None of the patients displayed severe illness and none required hospitalization; moreover, 7/20 patients were completely asymptomatic. Possible explanations for the minimal clinical impact of COVID-19 pandemic observed in our PID patients include high level of awareness, extra-precautions, and even self-isolation. It is also possible that only specific immune pathways (e.g. type I interferon signaling), may increase the risk for a more severe course of disease and these are not affected in many of the PID patients. In some cases, lack of an immune response actually may be a protective measure against the development of COVID-19 sequelae.

OTULIN deficiency in ORAS causes cell type-specific LUBAC degradation, dysregulated TNF signalling and cell death.

The deubiquitinase OTULIN removes methionine-1 (M1)-linked polyubiquitin signals conjugated by the linear ubiquitin chain assembly complex (LUBAC) and is critical for preventing TNF-driven inflammation in OTULIN-related autoinflammatory syndrome (ORAS). Five ORAS patients have been reported, but how dysregulated M1-linked polyubiquitin signalling causes their symptoms is unclear. Here, we report a new case of ORAS in which an OTULIN-Gly281Arg mutation leads to reduced activity and stability in vitro and in cells. In contrast to OTULIN-deficient monocytes, in which TNF signalling and NF-κB activation are increased, loss of OTULIN in patient-derived fibroblasts leads to a reduction in LUBAC levels and an impaired response to TNF Interestingly, both patient-derived fibroblasts and OTULIN-deficient monocytes are sensitised to certain types of TNF-induced death, and apoptotic cells are evident in ORAS patient skin lesions. Remarkably, haematopoietic stem cell transplantation leads to complete resolution of inflammatory symptoms, including fevers, panniculitis and diarrhoea. Therefore, haematopoietic cells are necessary for clinical manifestation of ORAS Together, our data suggest that ORAS pathogenesis involves hyper-inflammatory immune cells and TNF-induced death of both leukocytes and non-haematopoietic cells.

Pyogenic sacroiliitis in children: don't forget the very young.

Pyogenic sacroiliitis (PS) is rare with less than 100 pediatric cases reported in the medical literature. To better characterize PS in the pediatric population, we investigated a series of children presenting with PS. Retrospective data analysis was done at an academic tertiary center between the years of 2000 and 2017. All hospitalized children ≤ 16 years of age with PS were evaluated. Of the 894 children hospitalized with osteoarticular infections, 18 were diagnosed with PS (2%) and are included in the review. Two clinically distinct groups were identified. PS in infants (n = 13, 72.2%, mean age 1.1 years) had an indolent course and a faster recovery without any bacterial source identified. In contrast, the group of older children (n = 5, 27.8%, mean age 11.6 years) had a more complicated course and a higher rate of identified bacterial infections.Conclusion: We describe an under-recognized entity of PS in infants with a mild clinical course and fast recovery that differ from the "classical" septic sacroiliitis. Infants with PS did not suffer from invasive complications, and pathogen characteristics of older children were not identified. Infants with fever, irritability, decreased range of motion in the pelvic area, and pain during diapering should alert the clinician to this diagnosis. What is Known: • Pediatric pyogenic sacroiliitis is an extremely rare condition usually caused by Staphylococcus aureus with highest incidence in adolescents. • The diagnosis of PS is challenging due to its rarity and difficulty in assessing the sacroiliac joint. What is New: • We describe an under-recognized entity of PS in infants with a mild clinical course, without invasive complications and with fast recovery that differ from "classical" septic sacroiliitis. • Infants with fever, irritability, decreased range of motion in the pelvic area and pain during diapering should raise clinical suspicion of this diagnosis.