Table 2. Major and minor criteria for systemic mastocytosis diagnosis.

MC: Mast cells; BM: Bone marrow

Major Criterion	Minor Criterion
1. Multifocal, dense infiltrates of MCs (≥15 mast cells in aggregates) detected in sections of BM and/or other extracutaneous organs	1. Tryptase levels > 20 ng/ml
	2. Abnormal mast cell CD25 expression
	3. Presence of KIT D816V mutation
	4. Presence >25% atypical MCs