Genetics

Rearrangement of PDGFRA, PDGFRB, FGFR1, PCM1-JAK2, or ETV6-ABL1

Clonal population of T cells with aberrant phenotype

Clinical manifestations and laboratory findings

Anemia

Elevated serum tryptase levels

Elevated serum vitamin B12 levels

Endomyocardial fibrosis

Hypogranular or vacuolated eosinophils

Myelofibrosis

Splenomegaly

Thrombocytopenia

Angioedema

Circulating immune complexes (sometimes with serum sickness)

Hypergammaglobulinemia (especially IgE)

Skin abnormalities

Increased risk of future disorder

Acute lymphoblastic leukemia

Acute myeloid leukemia

T-cell lymphoma

Responsiveness to medications

Corticosteroids