Mast Cell Activation Syndrome and Mastocytosis: Initial Treatment Options and Long-Term Management.

Patients with clonal mast cell activation syndromes (MCAS) including cutaneous and systemic mastocytosis (SM) may present with symptoms of mast cell activation, but in addition can have organ damage from the local effects of tissue infiltration by clonal mast cells. Patients with nonclonal MCAS may have chronic or episodic mast cell activation symptoms with an increase in serum tryptase and/or urinary metabolites of histamine, prostaglandin D2, and leukotrienes. Symptoms of MCAS and SM can be managed by blockade of mediator receptors (H1 and H2 antihistamines, leukotriene receptor blockade), inhibition of mediator synthesis (aspirin, zileuton), mediator release (sodium cromolyn), anti-IgE therapy, or a combination of these approaches. Acute episodes of mast cell activation require epinephrine, and prolonged episodes may be addressed with corticosteroids. Patients with clonal mast cell syndromes may need a reduction in the number of mast cells to prevent severe symptoms including anaphylaxis and/or progression to aggressive diseases.