Background: The description of a monoclonal mast cell activation syndrome in patients with anaphylaxis, who fulfill one or two minor-criteria of mastocytosis, has led to a search for new unrecognized mast cell activation syndromes.
Objective: New classification of mast cell diseases including well-known diseases is provided in order to be able to better recognize and describe new entities.
Methods: The term mast cell activation has been defined by verifiable scientific objective and subjective criteria, and known and idiopathic mast cell activation syndromes have been classified.
Results: Mast cell activation cannot be defined by symptoms alone, as different diseases and conditions, including those with contribution of different cell types and somatization disorders may lead to similar symptoms. For this reason the preclinical checkpoint mast cell activation was defined to require typical symptoms in combination with demonstration of mast cell mediator release in (an acute) episode(s) as well as with a good response to mast cell mediator-directed therapy. Mast cell activation syndromes were classified in primary (e.g. mastocytosis), secondary (e.g. IgE-mediated allergy) and idiopathic forms.
Conclusion: Only through a deeper understanding of mast cell diseases, can new previously unrecognized idiopathic mast cell activation syndrome entities be described and analyzed.