Pediatric inflammatory multisystem syndrome (PIMS) is a new entity in children, likely associated with previous coronavirus disease 19 (COVID-19). Most of reports about PIMS come from countries particularly hit by the COVID-19 pandemic. Our aim was to investigate the nature of inflammatory syndromes in Poland (a country with low COVID-19 prevalence) and to perceive the emergence of PIMS in our country. On May 25th, we have launched a nationwide survey of inflammatory syndromes in children for retrospective (since 4th March 2020) and prospective data collection. Up to 28th July, 39 reported children met inclusion criteria. We stratified them according to age (<5 and ≥ 5 years old) and COVID-19 status. The majority of children had clinical and laboratory features of Kawasaki disease, probably non-associated with COVID-19. However, children ≥5 years of age had PIMS characteristics, and 9 children had COVID-19 confirmation. This is the first to our knowledge report of PIMS register from the country with low COVID-19 prevalence, and it proves that PIMS may emerge in any area involved in the COVID-19 pandemic. In a context of limited COVID-19 testing availability, other risk factors of PIMS, e.g. older age should be considered in the differential diagnosis of inflammatory syndromes in children.

Background & Aims: Multisystem inflammatory syndrome in children (MIS-C) is a rare, but severe complication of coronavirus disease 2019, commonly involving the gastrointestinal tract. Some children with MIS-C undergo appendectomy before the final diagnosis. There are several hypotheses explaining pathomechanism of MIS-C, with the central role of the viral antigen persistence in the gut, associated with lymphocyte exhaustion and immune system dysregulation. We aimed to examine appendectomy specimens obtained from MIS-C patients and analyze the pathological features of the disease and the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigens in the appendix. Methods: In this cross-sectional study we included 21 children with MIS-C who underwent appendectomy before the final diagnosis. MIS-C patients were recruited from the Polish national registry of inflammatory syndromes in children. The control group included 21 sex- and age-matched children with acute appendicitis (AA) unrelated to SARS-CoV-2 infection. Histological evaluation involved hematoxylin and eosin staining and immunohistochemical identification of lymphocyte subpopulations, programmed cell death protein 1, and SARS-CoV-2 nucleocapsid antigen. Results: Appendices of MIS-C patients lacked neutrophilic infiltrate of muscularis propria typical for AA (14 vs 95%, p<0.001). The proportion of CD20+ to CD5+ cells was higher in patients with MIS-C (p 0.04), as well as the proportion of CD4+ to CD8+ (p <0.001). We found no proof of SARS-CoV-2 antigen presence, nor lymphocyte exhaustion, in the appendices of MIS-C patients. Conclusions: Our findings describe pathomorphological features of the appendix in MIS-C and argue against the central role of SARS-CoV-2 persistence in the gut and concomitant lymphocyte exhaustion as the major triggers of MIS-C.

Introduction: Urticaria is a clinical entity presenting as wheals, angioedema, or both simul-taneously. Elevated D-dimer levels were reported in the course of chronic spontaneous urticaria. Data regarding D-dimer levels in acute urticaria in children are limited. Objectives: To assess potential associations between duration of glucocorticosteroid (GCS) therapy and D-dimer concentrations in children with acute urticaria. Patients, materials, and methods: Hospital records of 106 children (59 females), aged 5.57 ± 4.91 years, hospitalized in 2014–2018 were analyzed retrospectively. The study group consisted of pediatric patients admitted to the hospital due to severe acute urticaria resistant to anti-histaminic treatment that was ordered in the ambulatory care (out-patient clinic). Patients were divided into subgroups: no GCS treatment, short-duration treatment (up to 5 days) and long-duration treatment (6 and more days) GCS treatment. Simultaneously, patients received antihistaminic drugs. D-dimer level and other inflammatory factors such as white blood cell (WBC) count, platelet (PLT) count, and C-reactive protein (CRP) in each group were analyzed. Results: The D-dimer level was elevated in 51% of cases. In the subgroup with longer GCS treatment, D-dimer concentration was significantly higher in comparison to patients with a shorter GCS course. There were no differences in the distribution of CRP, PLT, and WBC concentrations between these subgroups. Conclusions: In the studied group of children, there was a tendency for higher D-dimer levels in patients, who required a longer GCS treatment. This finding is hypothesis-generating and requires further investigation to confirm if D-dimers can be used as a prognostic factor in acute urticaria in children.

Vaccines against infectious diseases may raise safety concerns in patients undergoing allergen immunotherapy (AIT). The objective of our study was to investigate influenza vaccine and other selected prophylactic vaccines coverage in patients treated with AIT and the attitude of physicians towards vaccinations in this group of patients. We conducted a questionnaire-based study among patients undergoing AIT and physicians. The patients’ survey evaluated influenza and other prophylactic vaccines coverage. The physicians’ survey assessed their experience and opinions on prophylactic vaccinations during AIT. In total, 176 patients (aged 18–79 years) and 120 doctors filled the questionnaires. Patients were assigned to two groups—inhaled allergens group (n = 101) and insect venoms group (n = 68). The number of patients who received any dose (36% and 45%, p = 0.26), as well as two or more doses (17% and 22%, p = 0.43) of influenza vaccine was comparable between two groups. However, in both groups there was a significant (p < 0.0001) decrease in influenza vaccine uptake after the beginning of AIT. Patients from the inhaled allergens group declared a higher tetanus vaccine rate (41% vs. 19%, p = 0.004). The groups did not differ in the pneumococcal and tick-borne encephalitis vaccination coverage. A majority of doctors believe that prophylactic vaccinations in patients undergoing AIT are safe and effective (96% and 94%, respectively); however, as many as 87% of them identify with the need to create clear recommendations regarding vaccinating patients undergoing AIT. Prophylactic vaccine coverage is not satisfactory among Polish adult patients undergoing AIT. Polish doctors are convinced of the validity of prophylactic vaccinations during AIT.

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