From Sensitisation to Tolerance: A Retrospective Study of Tree Nut and Peanut Allergy in Pediatric Patients

Background: Tree nut/Peanut (TN/PN) allergies are among the most common pediatric food allergies, often persisting into later life and posing significant clinical risks. The likelihood of tolerance acquisition varies, and predictive factors remain inadequately defined in clinical practice. Objective: To evaluate the clinical and laboratory features associated with anaphylaxis risk and tolerance development in pediatric patients with TN/PN allergy, and to determine the role of aeroallergen sensitization, comorbid atopic diseases, and skin test reactivity. Methods: In this retrospective, cross-sectional study, 121 children (0–18 years) diagnosed with TN/PN allergy at a tertiary allergy centre between 2016 and 2024 were analyzed. Data included allergic reaction history, comorbidities, total IgE, eosinophil counts, and prick-to-prick (PTP) test wheal sizes. Tolerance acquisition was defined based on oral food challenge, absence of reactions upon re-exposure, and clinical follow-up. Results: Multiple nut allergy was present in 81% of patients, with hazelnut (67%) and pistachio (62%) being most common. IgE-mediated reactions were predominant (91%), including urticaria (79%) and anaphylaxis (36%). During follow-up, 25% of patients developed tolerance, while 13% continued to experience anaphylaxis. Aeroallergen sensitisation, particularly to pollens, was significantly associated with reduced tolerance in almond and walnut allergy (p < 0.05). Persistent multi-nut allergy correlated with higher anaphylaxis risk (p < 0.01). Strong co-sensitisation was observed between pistachio–cashew (r = 0.686) and almond–walnut (r = 0.579). Notably, smaller PTP wheal sizes predicted tolerance acquisition (p < 0.05). Conclusion: Pediatric TN/PN allergy is frequently severe and persistent. Multiple nut allergy, aeroallergen sensitization, and larger PTP wheal sizes are significant risk factors for prolonged allergy and anaphylaxis. Early identification of these markers may improve risk stratification and guide individualized follow-up strategies.