WHO criteria for systemic mast cell disease
Major |
| Multifocal dense infiltrates of mast cells (MCs; more than 15 MCs aggregating) detected in sections of bone marrow (BM) and/or of other extracutaneous organ(s) by tryptase immunohistochemistry or other stains |
| Minor |
| In MCs, infiltrates detected in sections of BM or other extracutaneous organs, more than 25% of MCs are spindle-shaped or, in BM smears, atypical MCs comprise more than 25% of all MC |
| Detection of a c-kit point mutation at codon 816 in BM or blood or other extracutaneous organ(s) |
| Kit+ MCs in M or blood or other extracutaneous organ(s) coexpress CD2 and/or CD25 |
| Serum total tryptase concentration persistently greater than 20 ng/mL |
Major |
| Multifocal dense infiltrates of mast cells (MCs; more than 15 MCs aggregating) detected in sections of bone marrow (BM) and/or of other extracutaneous organ(s) by tryptase immunohistochemistry or other stains |
| Minor |
| In MCs, infiltrates detected in sections of BM or other extracutaneous organs, more than 25% of MCs are spindle-shaped or, in BM smears, atypical MCs comprise more than 25% of all MC |
| Detection of a c-kit point mutation at codon 816 in BM or blood or other extracutaneous organ(s) |
| Kit+ MCs in M or blood or other extracutaneous organ(s) coexpress CD2 and/or CD25 |
| Serum total tryptase concentration persistently greater than 20 ng/mL |
If 1 major and 1 minor or 3 minor criteria are fulfilled then the diagnosis of systemic mastocytosis is established.