The Spectrum of Mast Cell Activation Syndromes

Secondary mast cell activation syndromes are non-clonal processes involving reactive mast cell proliferation and/or mediator release disorders, stemming from an IgE mediated allergen, IgE-independent hypersensitivity reaction, or another immunologic disease. Allergic disorders are the most common cause of secondary MCAS, but other causes include neoplastic, autoimmune and chronic inflammatory disorders, as well as physical urticarias. Depending on the underlying condition driving secondary MCAS, prognosis is variable [2, 10, 12, 17].