The main objective of this study is to describe the distribution of reactogenic thresholds for pistachio. The secondary objectives are to 1) describe the clinical severity of allergic reactions to pistachio in an oral challenge test, 2) compare the reactogenic thresholds of pistachio and cashew nut on matched data and 3) evaluate predictive factors of a low reactogenic threshold

Nuts, including almonds, walnuts, cashews, pistachio and hazelnut, are among the food allergens most frequently involved in food allergies in children with an estimated prevalence. between 0.05 and 4.9%.

According to data from the Allergo-Vigilance Network, peanuts and the group of nuts, led by cashews, are alone responsible for 51.4% of food anaphylaxis in children.

The pistachio belongs to the same botanical family as the cashew nut (Anacardiumouest) and the mango (Mangifera indica): the anacardiaceae. Botanically, pistachio and cashew are closely related and can both be responsible for moderate to severe immediate allergic reactions. Furthermore, in a previous publication by the team, co-sensitization to pistachio was observed in 98% of children allergic to cashew nuts with only 34% confirmed allergic to pistachio.

In the case of allergy to both anacardiaceae, in a small number of patients, the investigators reported a reactogenic threshold for pistachio greater than or equal to that for cashew nuts.

To our knowledge, there is currently only one study that has evaluated the reactogenic threshold for pistachio, compared to other nuts.

Inclusion Criteria:

• Patients under 18 years of age who had a positive pistachio challenge test between January 2021 and December 2023, in the pediatric allergology unit of the Nancy CHRU.

Exclusion Criteria:

• Patients who had a questionable oral pistachio provocation test.
• Patients who had a negative pistachio oral provocation test.

Patients under 18 years of age who had a positive pistachio challenge test between January 2021 and December 2023, in the pediatric allergology unit of the Nancy CHRU