Methods: Case report.
Results: We report an 18-year-old girl with asthma and allergic rhinitis who developed mild chronic urticaria and frequent episodes of anaphylaxis characterized by sudden-onset pruritus, erythema, hives, abdominal pain, diarrhea, stridor and wheezing. Anaphylaxis occured every 3-30 days during 16 months, presenting spontaneously or after eating, with no specific triggers. Several episodes were witnessed and confirmed by experienced allergists. All episodes were promptly relieved by intramuscular epinephrine. Several food challenges to suspicious foods or additives were negative. Laboratory studies showed elevated total IgE of 334 UI/ml. Systemic mastocytosis was ruled out with normal baseline serum total and free tryptase, negative D816V c-Kit mutation, and normal histopathology of skin nevi, bone marrow and stomach. Ga68-PET/CT and intraplatelet serotonin ruled out carcinoid. The patient failed to respond to H1 and H2 blockers, montelukast, ketotifen, high-dose systemic corticosteroids, mycophenolate mofetil, omalizumab and elimination diets. The patient ceased to have anaphylaxis and urticaria 10 days after two doses of rituximab 1000 mg every 14 days. After 6 months, B cell count normalized and the patient restarted chronic urticaria symptoms and IA every 3-7 days. Retreatment with two doses of rituximab 500 mg every 14 days led again to full remission of anaphylaxis with follow-up of 4 months after retreatment.
Conclusions: This is the first report of successful treatment of IA with rituximab. This case suggests B-cell depletion as a novel highly effective treatment for IA.
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