D1.54 - Nut Allergy in the Spotlight: The Crucial Role of Oral Provocation Tests

Background:The prevalence of IgE-mediated food allergies has risen in recent years, creating significant burden for patients and their families. Advances in diagnostic methods, such as molecular allergy diagnostics (MAD) and skin prick testing (SPT), have improved our ability to identify allergens; however, effective management of food allergies remains complex. This case highlights the pivotal role of oral provocation tests (OPT), which remain the gold standard for providing definitive insights into clinical reactivity and guiding safe dietary management.

Case report: A 5-year-old girl was referred to our Allergy Clinic for further evaluation, following an extensive history of nut-related hypersensitivity. The patient had a history of atopic dermatitis, no respiratory allergies were reported. By the age of 1, she experienced multiple episodes of transient rashes after consuming peanut butter, sesame and walnut tahini, prompting an allergy consultation. Initial investigation revealed positive SPTs and sIgE for peanut, walnut, hazelnut, cashew, as well as sIgE for sesame, pecan and brazil nuts. The subsequent OPT with cashews and peanuts resulted in hives and vomiting, while macadamia provocation was unremarkable. Prior to her referral to our clinic, further diagnostic investigations revealed a gradual decrease in nut sensitization. However, the patient experienced two additional episodes: perioral rash and sore throat following pumpkin seed ingestion and isolated abdominal pain after consuming a hazelnut-containing pastry. Our approach included prick-to-prick (PTP) testing with raw and roasted nuts and seeds and MAD, followed by OPT.

Results: PTP testing showed negative results for cashew and pistachio but positive results for pumpkin seeds. MAD identified sensitization to 2S albumins in peanuts, walnuts, hazelnuts, brazil nuts, pecans, sesame, pumpkin, and poppy seeds, proteins associated with potentially severe allergic reactions, while confirming no sensitization to cashew or pistachio. Subsequent OPT with cashew and pistachio, administered in incremental doses (¼ tsp to 1 tbsp every 20 minutes), revealed no signs of hypersensitivity. Based on these findings, we recommended incorporating daily consumption of cashew and pistachio into the patient’s diet and advised strict avoidance of pumpkin seeds.

Discussion:This case underscores the complexity of food allergy diagnosis and management, particularly when addressing potentially severe sensitization patterns. While modern diagnostic tools offer valuable insights, OPTs remain the definitive method for establishing clinical reactivity, enabling tailored dietary management and enhancing patient safety and quality of life.