The Spectrum of Mast Cell Activation Syndromes

Patients with idiopathic MCAS meet the three criteria for MCAS, but after a thorough evaluation, there is no identified primary/clonal driver of disease, no secondary/reactive driver of disease, no neoplastic mast cells, and no IgE-dependent allergy. Since the etiology is unknown, treatment is aimed at symptomatic relief and mast cell stabilization. Prognosis is variable in these patients [10, 12]. Idiopathic anaphylaxis, a systemic reaction resulting from mast cell activation, entails fulfilling anaphylaxis criteria (2 or more organ systems, including mucocutaneous, respiratory, gastrointestinal, and cardiovascular) without an identified inciting allergen [40, 41].