Purpose of review: To illustrate features of allergy in mastocytosis.
Recent findings: The rates of atopy in patients with mastocytosis have generally been found to be similar to those of the normal population, although the incidence of anaphylaxis is much higher in mastocytosis. Introduction of objective pathologic criteria by the WHO for the diagnosis of mastocytosis has greatly facilitated the workup of patients with suspected mastocytosis, and has led to identification of mast cell disease in a subset of patients with anaphylaxis. There is increasing evidence that an activating c-kit mutation (D816V) exists in a subset of patients with recurrent mast cell activation symptoms who have normal-appearing bone marrow biopsies in routine evaluations without skin lesions. The genetic deficiency of alpha tryptase has not been found to influence serum tryptase levels in patients with mastocytosis.
Summary: Pathologic mast cell activation is a key finding in both allergic diseases and mastocytosis, albeit caused by entirely different mechanisms. Mastocytosis should be suspected in patients with recurrent anaphylaxis, who present with syncopal or near-syncopal episodes without associated hives or angioedema.