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Gonçalo. Martins-Dos-Santos1, Pedro Coelho1, Sara Prates1, Paula Leiria Pinto1

1 - Serviço de Imunoalergologia, Centro Hospitalar Universitário de Lisboa Central

- EAACI Hybrid Congress 2022

BACKGROUND: Oat is a cereal from the Poaceae family, which has become very popular in the occidental diet due to its high nutritional value. The very few cases of oat allergy described in the literature show variable patterns of reactivity to other cereals.
CASE REPORT: A 13-year-old boy, with rhinitis, was referred to our Department after two anaphylactic reactions. One hour before the onset of the 1st episode, he had eaten a home-made cake (oat flour, cocoa, eggs, and mixed nuts). The 2nd episode occurred four months later, minutes upon eating a cereal bar (oat, wheat, milk, and “may contain” egg, soy, peanut, and hazelnut). No cofactors were identified. Since the last episode, he had tolerated peanut and several nuts, and he was regularly eating eggs, milk, soy, chocolate, and all cereals but oat. Skin prick tests were positive to oat flour, peanut, almond, sesame, house dust mites (HDM), and grass pollen, and negative to non-specific lipid transfer protein, hazelnut, walnut, cashew, and pistachio. Prick-prick tests were positive to oat and almond and negative to peanut and remaining nuts. Blood tests showed a total IgE of 734 KUI/L and sIgE to oat of 68.1 KUA/L. sIgE to other cereals (barley, rye, wheat, rice, maize), almond, and peanut was all under 5 KUA/L. ImmunoCap ISAC was strongly positive to Phl p1 and several HDM allergens. It was weakly positive to Ana o 2 and Gly m 6 and negative to all other storage proteins and wheat proteins in the test. Although almond allergy has not yet been excluded, we assumed the diagnosis of oat allergy. He keeps free ingestion of all nuts except almond, for which we are planning an oral challenge test.
DISCUSSION AND CONCLUSION: Despite being sensitized to all tested cereals, he was reacting only to oats, for which the sIgE was much higher. The detection of low sIgE to other cereals was probably due to their low cross-reactivity with oat or could also be related to grass pollen sensitization. An oral challenge test will be helpful to clarify the clinical relevance of the sensitization to almond. In conclusion, this case highlights a rare food allergy with no need for extensive food avoidance, despite the concomitant sensitization to other cereals. More studies about oat allergens are needed, to improve the management of this allergy, expected to increase in the upcoming years.

Palavras Chave: alergia, alimento, aveia