From Reaction to Resolution: Tolerance Outcomes in Pediatric IgE- and Non-IgE-Mediated Fish Allergy

Fish is a potent allergen source that can induce both IgE-mediated and non-IgE-mediated reactions, particularly food protein-induced enterocolitis syndrome (FPIES). Prevalence and clinical course of fish allergy vary by age and geographic region, with limited data on tolerance development. This study aims to compare clinical and laboratory characteristics of IgE- and non-IgE-mediated fish allergy in children and to identify factors influencing tolerance.

This study included 47 children (6 months-18 years) diagnosed with fish allergy from 2010 to 2023 at a tertiary pediatric allergy clinic. Classification into IgE and non-IgE groups was based on clinical presentations, skin prick test (SPT), and specific IgE (sIgE). Tolerance was defined by negative oral food challenge (OFC) and dietary reintroduction.

Among 47 patients (25 IgE-mediated, 22 non-IgE/FPIES), reactions included FPIES (46.8%), anaphylaxis (27.7%), and urticaria/angioedema (25.5%). Seven IgE and three non-IgE patients were excluded due to parental refusal of OFC. OFCs were not done in 9 IgE patients with high sIgE/SPT. OFCs confirmed tolerance in all tested IgE (9/9) and 7/17 non-IgE patients. Age at tolerance was similar between the groups. Severe reactions, inhalation-related symptoms, multiple fish allergies, and large SPT wheals predicted lower tolerance in IgE group (respectively, p = 0.028, p = 0.002, p = 0.046, p = 0.030), while older age at last reaction predicted persistence in non-IgE group (p = 0.017). Anchovy and salmon were most tolerated.

This first study evaluating IgE- and non-IgE-mediated fish allergies with OFCs shows substantial tolerance rates, highlighting the need for timely OFCs and personalized care addressing psychosocial factors like anxiety.