•CBC with differential•Liver function tests, including serum albumin, serum LDH, and serum ALP•DEXA bone density scan•Serum tryptase•Consideration of skin biopsy•Bone marrow or other extracutaneous organ biopsy○Tryptase○CD117, CD25, CD30, and/or CD2•Molecular testing○High-sensitivity c-KIT D816V (e.g., PCR) and other KIT exon mutations○Myeloid mutation panel for possible additional mutations○FIP1L1-PDGFRA fusion if eosinophilia present. This evidence concerns the gene TNFRSF8 and Increased total eosinophil count.