D2.315 - Clinical Characteristics and Diagnostic Challenges in Pediatric Peanut and Tree Nut Allergies: The Impact of Unnecessary Elimination

Peanut and tree nut (PTN) allergies are global health concerns characterized by persistent sensitization and a high risk of systemic reactions. This study evaluates clinical characteristics, co-sensitization patterns, and the diagnostic accuracy of skin prick tests (SPT) and serum-specific IgE (sIgE) levels compared to oral food challenges (OFC).

This retrospective study included 42 children (median age: 90 months) evaluated at a tertiary allergy clinic. Inclusion criteria required age 6 months to 18 years, clinical suspicion of PTN allergy, or nut avoidance with a completed diagnostic workup. Diagnostic procedures followed EAACI guidelines, utilizing SPTs (positive: wheal ≥3 mm) and/or sIgE measurements via ImmunoCAP (positive: >0.35 kU/L) for peanut, walnut, cashew, hazelnut, pistachio, and almond. Standardized open OFCs were performed to confirm clinical allergy. Sensitization patterns assessed cross-reactivity, particularly within the Anacardiaceae family. Patients were stratified by elimination rationale: documented reaction history versus prophylactic avoidance without prior symptoms.

Of the children, 8 (19%) had a positive OFC, most commonly to walnut (23,5%) and cashew (23,1%). The cohort exhibited a high atopic burden: 92.9% had ≥1 atopic disease, 61.9% had current atopic dermatitis (AD), and 78.6% had a history of infantile AD, with a median serum total IgE of 232.0 IU/mL. While sensitization rates were prevalent for cashew and walnut (76.2% and 75%, respectively), positive OFC was disproportionately low (23.1% and 23.5%, respectively). All challenges for peanut, pistachio, and almond were tolerated. Strong co-sensitization occurred within the Anacardiaceae family; 85.7% of pistachio-sensitized patients were also sensitized to cashew. In the elimination group (n = 12), while high sensitization rates (>75% for hazelnut and cashew) were observed, all of them passed the OFC.

Our study demonstrates a significant discrepancy between sensitization and true clinical allergy. The high prevalence of atopic dermatitis aligns with the Dual Allergen Exposure Hypothesis, as the skin is the entry point for subsequent allergies. While Anacardiaceae show robust cross-sensitization, positive tests frequently lead to unwarranted restrictions. Clinicians must exclude food allergy with OFC, particularly in patients practicing prophylactic avoidance without a reaction history.