Table 2.

World Health Organization diagnostic criteria for systemic mastocytosis (modified from Valent et al[3])

Major criterion

Multifocal dense infiltrates of MCs (> 15 MCs in aggregates) in bone marrow biopsy and/or in sections of other extracutaneous organ(s)

Minor criteria

(1) > 25% of all MCs are atypical cells on bone marrow smears or are spindle-shaped in MC infiltrates detected on sections of extracutaneous organ(s)

(2) c-kit point mutation at codon 816 in the bone marrow or in another extracutaneous organ

(3) MCs in the bone marrow or in another extracutaneous organ express CD2 and/or CD25

(4) Serum tryptase levels > 200 ng/mL (this criterion is valid only if AHNMD-SM has been excluded)

MCs: Mast cells; AHNMD-SM: Associated hematopoietic clonal non-MC lineage disease systemic mastocytosis.