IMMEDIATE AND DELAYED REACTIONS AFTER PEANUT INGESTION: A DIAGNOSTIC CHALLENGE

Introduction: Food protein-induced enterocolitis syndrome (FPIES) is a distinct entity from IgE-mediated food allergy We present a case in which a patient has a history consistent with both diagnoses to a single food allergen Case Description: An exclusively breast-fed 5-month-old female initially presented with repetitive emesis 2 hours after consumption of egg, which was accompanied by a delayed rash Given overlap of symptoms, testing was performed as a diagnostic aid for distinguishing between FPIES and IgE mediated food allergy Egg white IgE was 0 43 ku/L, and peanut IgE was 0 26 ku/L with completely negative components After counseling and shared decision making, the caregiver was motivated to introduce small amounts of peanut at home during COVID as a preventative intervention for the development of IgE mediated allergy After peanut ingestion, the infant first had delayed emesis At a later date, the caregiver gave a reduced dose of peanut and the patient had an immediate reaction of hives and facial edema requiring epinephrine Discussion: FPIES and IgE-mediated allergy can be differentiated by history with attention to timing and accompanying symptoms It is known that patients with FPIES can develop IgE antibodies to trigger foods (atypical FPIES), signifying a likelihood of a more protracted FPIES course and transition to acute reactions In our patient however, peanut ingestion resulted in distinct episodes with both FPIES and IgE-mediated symptoms, perhaps signifying a further need for understanding of the relationship between the two disorders