Anaphylactic Reactions After Discontinuation of Hymenoptera Venom Immunotherapy: A Clonal Mast Cell Disorder Should Be Suspected

Publication date: Available online 16 December 2017
Source:The Journal of Allergy and Clinical Immunology: In Practice
Author(s): Patrizia Bonadonna, Roberta Zanotti, Mauro Pagani, Massimiliano Bonifacio, Luigi Scaffidi, Elisa Olivieri, Maurizio Franchini, Federico Reccardini, Maria Teresa Costantino, Chiara Roncallo, Marina Mauro, Elisa Boni, Fabio Lodi Rizzini, Maria Beatrice Bilò, Anna Rosaria Marcarelli, Giovanni Passalacqua
BackgroundUp to 75% of patients with severe anaphylactic reactions after Hymenoptera sting are at risk of further severe reactions if re-stung. Venom immunotherapy (VIT) is highly effective in protecting individuals with ascertained Hymenoptera venom allergy (HVA) and previous severe reactions. After a 3- to 5-year VIT course, most patients remain protected after VIT discontinuation. Otherwise, a lifelong treatment should be considered in high-risk patients (eg, in mastocytosis). Several case reports evidenced that patients with mastocytosis and HVA, although protected during VIT, can re-experience severe and sometimes fatal reactions after VIT discontinuation.ObjectiveTo evaluate whether patients who lost protection after VIT discontinuation may suffer from clonal mast cell disorders.MethodsThe survey describes the characteristics of patients who received a full course of VIT for previous severe reactions and who experienced another severe reaction at re-sting after VIT discontinuation. Those with a Red Española de Mastocitosis score of 2 or more or a serum basal tryptase level of more than 25 ng/mL underwent a hematological workup (bone marrow biopsy, KIT mutation, expression of aberrant CD25) and/or skin biopsy.ResultsNineteen patients (mean age, 56.3 years; 89.5% males) were evaluated. All of them had received at least 4 years of VIT and were protected. After VIT discontinuation they were re-stung and developed, in all but 1 case, severe anaphylactic reactions (12 with loss of consciousness, in the absence of urticaria/angioedema). Eighteen patients (94.7%) had a clonal mast cell disorder, 8 of them with normal tryptase.ConclusionsLooking at this selected population, we suggest that mastocytosis should be considered in patients developing severe reactions at re-sting after VIT discontinuation and, as a speculation, patients with mastocytosis and HVA should be VIT-treated lifelong.