Pseudo-idiopathic anaphylaxis in a patient with mastocytosis

Insect stings are meanwhile established triggers of anaphylactic reactions in patients suffering from mastocytosis. Except Hymenoptera venom, however, work-up of allergic reactions in mastocytosis patients is often incomplete resulting in the erroneous diagnosis of an idiopathic anaphylaxis. We report on a 61-year-old patient presenting for the first time with indolent systemic mastocytosis. For the last 14 years, this patient had developed 30 anaphylactic reactions, which had been associated with physical activity and infections, and of which the majority had been severe. Careful work-up confirmed among others a sensitization to the lipid transfer protein (LTP) of the peach, Pru p 3 and the PR-10 protein Bet v 1. Furthermore, the patient recalled anaphylactic reactions to apples, pears, cherries, grapes, lettuce, and tomatoes. Oral challenge tests with apple and pear confirmed these triggers. After starting the patient on omalizumab, it was possible to ease dietary restrictions without a recurrence of anaphylactic reactions. LTP-associated food allergy is very rare in Central and Northern Europe. Nevertheless, work-up of allergic reactions in mastocytosis patients should always include uncommon triggers, thereby minimizing the risk of erroneously diagnosing an idiopathic anaphylaxis. © 2021 Dustri-Verlag Dr. Karl Feistle