International Consensus Classification (ICC) Diagnostic Criteria for Systemic Mastocytosis

Multifocal dense infiltrates of tryptase- and/or CD117-positive mast cells (≥15 mast cells in aggregates) detected in sections of bone marrow and/or other extracutaneous organ(s)

In bone marrow biopsy or in section of other extracutaneous organs, >25% of mast cells are spindle-shaped or have an atypical immature morphology

Mast cells in bone marrow, peripheral blood, or other extracutaneous organs express CD25, CD2, and/or CD30, in addition to mast cell markers

KIT D816V mutation or other activating KIT mutation detected in bone marrow, peripheral blood, or other extracutaneous organs

Elevated serum tryptase level, persistently >20 ng/mL. In cases of SM-AMN, an elevated tryptase does not count as a SM minor criterion