Background: Although non-steroidal anti-inflammatory drug hypersensitivity (NSAID-H) has been widely studied in adults, there is still a lack of data regarding the features and phenotypes of NSAID-H in children. Our aim was to define risk factors and different phenotypes according to clinical patterns. Methods: Patients with a history of reaction to any NSAIDs referred between January 2012 and October 2014 were included. After completing a European Network for Drug Allergy (ENDA) questionnaire, initial skin and/or oral provocation tests (OPTs) were performed for the offending drug. Additional OPTs were done with aspirin in case of NSAID-H to determine cross-reactivity. NSAID-hypersensitive patients were defined as being either a selective responder (SR) or cross-intolerant (CI) and further categorized according to either the ENDA/GA²LEN classification or an alternative scheme by Caimmi et al. [Int Arch Allergy Immunol 2012;159:306-312]. Results: Among 121 patients [58.7% male, average age 7.8 years (4.7-10.8)] with 161 NSAID-related reactions, 110 patients with 148 reactions were assessed. NSAID-H was diagnosed in 30 (27%) patients with 37 (25%) reactions. Multivariate regression analysis revealed that an immediate-type reaction and respiratory symptoms during the reaction increased the risk of a reproducible NSAID-related reaction (OR 3.508, 95% CI 1.42-8.7, p = 0.007; OR 3.951, 95% CI 1.33-11.77, p = 0.014, respectively). Additional OPTs revealed 13 SRs and 14 CIs. A family history of allergic disease was more frequent in CIs compared to SRs (57.1 vs. 15.4%, p = 0.031). Reactions belonging to CIs were more frequently characterized by angioedema compared to those of SRs (81.3 vs. 46.2%, p = 0.019). SRs and CIs were further classified as single NSAID-induced urticaria/angioedema and/or anaphylaxis (n = 13), NSAID-induced urticaria/angioedema (n = 7), NSAID-exacerbated cutaneous disease (n = 2) and NSAID-exacerbated respiratory disease (n = 1). Four CIs could not be categorized according to either classification system. One SR could not be categorized according to ENDA/GA²LEN. Conclusion: During childhood, NSAID-H exhibits different phenotypes and the majority of them can be categorized with current classification systems; however, classifications based on adult data may not exactly fit NSAID-H in paediatric patients.

The etiology of CSU in children was mostly idiopathic despite detailed investigation. In childhood, the natural course of CSU was favorable, and nearly half of the patients recovered after 5 years of disease duration. A high UAS7 at admission seemed to be a significant risk factor for the persistence of symptoms.

Biallelic mutations in the genes encoding CD27 or its ligand CD70 underlie inborn errors of immunity characterized predominantly by EBV-associated immune dysregulation, such as chronic viremia, severe infectious mononucleosis, hemophagocytic lymphohistiocytosis (HLH), lymphoproliferation and malignancy. A comprehensive understanding of the natural history, immune characteristics and transplant outcomes has remained elusive. Here, in a multi-institutional global collaboration, we collected clinical information of 49 patients from 29 families (CD27 n=33, CD70 n=16), including 24 previously unreported individuals and identified a total of 16 distinct mutations in CD27, and 8 in CD70, respectively. The majority (90%) of patients were EBV+ at diagnosis, but only ~30% presented with infectious mononucleosis. Lymphoproliferation and lymphoma were the main clinical manifestations (70% and 43%, respectively), and 9 of the CD27-deficient patients developed HLH. Twenty-one (43%) patients developed autoinflammatory features including uveitis, arthritis and periodic fever. Detailed immunological characterization revealed aberrant generation of memory B and T cells, including a paucity of EBV-specific T cells, and impaired effector function of CD8+ T cells, thereby providing mechanistic insight into cellular defects underpinning the clinical features of disrupted CD27/CD70 signaling. Nineteen patients underwent allogeneic hematopoietic stem cell transplantation (HSCT) prior to adulthood predominantly because of lymphoma, with 95% survival without disease recurrence. Our data highlight the marked predisposition to lymphoma of both CD27- and CD70-deficient patients. The excellent outcome after HSCT supports the timely implementation of this treatment modality particularly in patients presenting with malignant transformation to lymphoma.

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A relationship between serum basal tryptase (sBT) levels, anaphylactic reactions, and clonal mast cell diseases was shown recently in adults with venom allergy, but the relationship between sBT levels and IgE-mediated food allergy and anaphylaxis is not known. In this study, children with food allergy (FA; n = 167) were analyzed in two groups according to the presence (FA+/A+; n = 79) or absence of anaphylaxis (FA+/A-; n = 88) and were compared with a control group (n = 113). Median sBT values in FA+/A+, FA+/A-, and control groups were 4.0 ng/ml (2.8-5.8), 3.6 (2.3-4.5), and 3.3 (2.4-4.4), respectively (P = 0.022). sBT measurements higher than the cutoff values of 5.7 and 14.5 were associated with 50% and 90% predicted probabilities, respectively, of moderate to severe anaphylaxis. Children with tree nuts/peanut allergies had significantly higher levels of sBT than children with milk and egg allergy (P = 0.022). Results suggest that sBT levels may predict moderate to severe anaphylaxis in children with food allergy, which may follow a particular pattern according to the food allergy phenotype.