Dilemma of Mast Cell Activation Syndrome: Overdiagnosed or Underdiagnosed?
Mast cell activation syndrome (MCAS) is a heterogeneous entity resulting from acute, episodic, and systemic mast cell (MC) activation.1,2 There is no single pathognomonic tissue marker or blood test to confirm or rule out MCAS. Instead, according to criteria endorsed by the major research and clinical networks in Europe (European Competence Network on Mastocytosis [ECNM]), and the United States (American Initiative in Mast Cell Diseases [AIM]), all 3 of the following findings must be fulfilled: (1) symptoms of MC activation in at least 2 organ systems; 2) objective documentation of elevation of mediators that are known to be secreted by MCs with reasonable selectivity; and (3) at least a partial response of clinical symptoms to drugs that target these mediators.