TABLE 1.

Diagnostic criteria for systemic mastocytosis [a] [Copyright: ©2016 Cohen.]

Major criteria

The presence of multifocal dense infiltrates of mast cells in the bone marrow or other extracutaneous organs, confirmed by special stains such as mast cell tryptase (greater than15 mast cells aggregating)

Minor criteria

Atypical mast cell morphology: in mast cell infiltrates in the bone marrow or other extracutaneous organs, greater than 25% of the mast cells are spindle-shaped or otherwise atypical; or in bone marrow smears, greater than 25% of the mast cells are spindle-shaped or otherwise atypical

Aberrant mast cell immunophenotype: mast cells in extracutaneous organs (CD117) co-express either CD2 or CD25 or both, as determined by flow cytometry

Activating point mutation of KIT in codon 816 is present in extracutaneous organs

Baseline serum tryptase level is persistently elevated (greater than 20 ng/ml); this does not count in patients who have an associated clonal hematologic non-mast cell disease (AHNMD)

[a] The diagnosis of systemic mastocytosis is fulfilled either by: (1) the presence of the major criterion plus one minor criterion or (2) the presence of at least three minor criterion.