Serum amyloid A (SAA) is an acute phase protein with a significant importance for patients with inflammatory rheumatic diseases (IRD). The central role of SAA in pathogenesis of IRD has been confirmed by recent discoveries, including its involvement in the activation of the inflammasome cascade and recruitment of interleukin 17 producing T helper cells. Clinical utility of SAA in IRD was originally evaluated nearly half a century ago. From the first findings, it was clear that SAA could be used for evaluating disease severity and monitoring disease activity in patients with rheumatoid arthritis and secondary amyloidosis. However, cost-effective and more easily applicable markers, such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), overwhelmed its use in clinical practice. In the light of emerging evidences, SAA has been discerned as a more sensitive biomarker in a wide spectrum of IRD, especially in case of subclinical inflammation. Furthermore, a growing number of studies are confirming the advantages of SAA over many other biomarkers in predicting and monitoring response to biological immunotherapy in IRD patients. Arising scientific discoveries regarding the role of SAA, as well as delineating SAA and its isoforms as the most sensitive biomarkers in various IRD by recently developing proteomic techniques are encouraging the revival of its clinical use. Finally, the most recent findings have shown that SAA is a biomarker of severe Coronavirus disease 2019 (COVID-19). The aim of this review is to discuss the SAA-involving immune system network with emphasis on mechanisms relevant for IRD, as well as usefulness of SAA as a biomarker in various IRD. Therefore, over a hundred original papers were collected through an extensive PubMed and Scopus databases search. These recently arising insights will hopefully lead to a better management of IRD patients and might even inspire the development of new therapeutic strategies with SAA as a target.

Introduction: While the clinical course of SARS-CoV-2 infection seems to be milder or asymptomatic within the pediatric population, growing attention has been laid to the rare complication elicited by virus, multisystem inflammatory syndrome in children temporarily associated with COVID-19 (MIS-C). Published definition and criteria of MIS-C include persistent fever, multisystem involvement, and elevated markers of inflammation, without obvious microbial inflammation or other plausible diagnosis. However, the aim of this case report is to emphasize the diversity of symptoms of MIS-C, beyond the defined criteria.Case Presentation: We present a 10-year-old boy with 8p23.1 microdeletion syndrome and multiple comorbidities who initially came to our attention due to hematuria, persistent fever, rash, and elevated markers of inflammation. Within the next 2 days, his condition worsened despite the broad-spectrum antibiotic therapy. Assuming his past history of SARS-CoV-2 exposure, MIS-C was suspected. A high level of clinical suspicion was further supported by significant clinical features (vomiting, abdominal pain, conjunctivitis, arrhythmia, and mild left ventricular systolic dysfunction with pleural effusion) along with laboratory findings (elevated ESR, CRP, proBNP, D-dimers and fibrinogen, positive IgG SARS-CoV-2 antibodies, and negative microbiological cultures). The patient was given intravenous immunoglobulin (IVIG) and began to show instantaneous clinical and laboratory improvement.Conclusion: Despite numerous reports of MIS-C cases in children, there are still many uncertainties regarding the clinical presentation and laboratory findings, as well as mechanisms beyond this intriguing disorder. In our case, for the first time hematuria is reported as an early symptom of MIS-C. We strongly believe that reporting various manifestations and outcomes in MIS-C patients will lead to improved diagnosis, treatment, and overall understanding of this novel inflammatory condition.

IntroductionAs the global pandemic continues, new complications of COVID-19 in pediatric population have turned up, one of them being hemolytic uremic syndrome (HUS), a complement-mediated thrombotic microangiopathy (CM-TMA) characterized by triad of thrombocytopenia, microangiopathic hemolytic anemia and acute kidney injury (AKI). With both multisystem inflammatory syndrome in children (MIS-C) and HUS sharing complement dysregulation as one of the key factors, the aim of this case report is to highlight differences between these two conditions and also emphasize the importance of complement blockade as a treatment modality.Case reportWe describe a 21-month-old toddler who initially presented with fever and confirmed COVID-19. His condition quickly deteriorated and he developed oliguria, accompanied with diarrhea, vomiting and oral intake intolerance. HUS was suspected, supported with compelling laboratory findings, including decreased platelets count and C3 levels, elevated LDH, urea, serum creatinine and sC5b-9 and presence of schistocytes in peripheral blood, negative fecal Shiga toxin and normal ADAMTS13 metalloprotease activity. The patient was given C5 complement blocker Ravulizumab and started to display rapid improvement.ConclusionAlthough reports of HUS in the setting of COVID-19 continue to pour in, the questions of exact mechanism and similarities to MIS-C remain. Our case for the first time accentuates the use of complement blockade as a valuable treatment option in this scenario. We sincerely believe that reporting on HUS as a complication of COVID-19 in children will give rise to improved diagnosis and treatment, as well as better understanding of both of these intricating diseases.

6.027 (95% CI, 3.996-9.090) for inotropic drug usage, 2.348 (95% CI, 1.547-3.564) for RBC transfusion requirement, 1.655 (95% CI, 1.162-2.356) for RDW>15.1% and 2.950 (95% CI, 1.933-4.503) for PLT < 150 × 103/uL.The AKI is associated with prolonged hospitalization and increased mortality.among critically ill children. In patients with AKI, the need for mechanical ventilation, CRRT and inotropic drugs was statistically associated with mortality.