Major criterion Minor criteria
Multifocal, dense infiltrates of mast cells (≥15 mast cells in aggregates) detected on bone marrow biopsy and/or on extracutaneous organs biopsy >25% of mast cells in the infiltrate are spindle-shaped or have atypical morphology on bone marrow/ extracutaneous organs biopsy OR >25% of mast cells in bone marrow aspirate are immature or atypical
Detection of KITD816V mutation
Expression of CD25±CD2 on mast cells
Serum total tryptase persistently >20 ng/mL (in the absence of associated myeloid neoplasm)