Mast Cell Activation Syndrome (MCAS) Mast Cell Activation Syndrome: A Review. Mast Cell Activation Syndrome: A Review. Mast Cell Activation Syndrome (MCAS) Mast Cell Activation Syndrome: A Review. Mast Cell Activation Syndrome: A Review. Mast Cell Activation Syndrome (MCAS) http://www.ncbi.nlm.nih.gov/pubmed/23179866 MCAD