Check for updatesReceived:10 April 2023Revised:28 April 2023Accepted:4 May 2023D0t:10.1002/ajh26966CRITICAL REVIEWWILEYThe international consensus classification of eosinophilicdisorders and systemic mastocytosisSa A.Wang1 Attilio Orazi2 Jason Gotlib3 Andreas Reiter4Alexandar Tzankov5 Robert P.Hasserjian5 Daniel A.Arber7Ayalew Tefferi8Department of Hematopathology.TheUniversity of Texas MD Anderson CancerAbstractCenter,Houston,Texas,USABased on new data and increased understanding of disease molecular genetics,the2Department of Pathology.Texas TechUniversity Health Science Center,Lubbock.international consensus classification(ICC)has made several changes in the diagnosisTexas.USAand classification of eosinophilic disorders and systemic mastocytosis.Myeloid/3Division of Hematology.Department oflymphoid neoplasms with eosinophilia (M/LN-eo)and gene rearrangements haveMedicine,Stanford University School ofMedicine/Stanford Cancer Institute,been renamed as M/LN-eo with tyrosine kinase gene fusions(M/LN-eo-TK).The cat-California,USAegory has been expanded to include ETV6:ABL1 and FLT3 fusions,and to acceptDepartment of Hematology and Oncology.University Hospital Mannheim,HeidelbergPCM1:JAK2 and its genetic variants as formal members.The overlaps and differencesUniversity,Mannheim,Germanybetween M/LN-eo-TK and BCR::ABL1-like B-lymphoblastic leukemia (ALL)/de novoSDepartment of Pathology.UniversitatsspitalT-ALL sharing the same genetic lesions are addressed.Besides genetics,ICC for theBasel,Basel,SwitzerlandDepartment of Pathology.Massachusettsfirst time has introduced bone marrow morphologic criteria in distinguishing idio-General Hospital,Boston,Massachusetts,USApathic hypereosinophilia/hypereosinophilic syndrome from chronic eosinophilicDepartment of Pathology.University ofleukemia,not otherwise specified.The major diagnostic criteria for systemic masto-Chicago,Chicago,lllinois,USADivision of Hematology.Mayo Clinic.cytosis(SM)in the ICC remain largely based on morphology,but several minor modi-Rochester,Minnesota,USAfications/refinements have been made in criteria related to diagnosis,subclassification,and assessment of disease burden(B-and C-findings).This reviewCorrespondenceSa A.Wang.Department of Hematopathology.is to focus on the ICC updates related to these disease entities,illustrated throughThe University of Texas MD Anderson Cancerchanges related to morphology,molecular genetics,clinical features,prognosis,andCenter,6565 MD Anderson Boulevard.Houston,TX 77030,USA.treatment.Two practical algorithms are provided in navigating through the diagnosisEmail:swang5@mdanderson.organd classification systems of hypereosinophilia and SM.Attilio Orazi,Department of Pathology.TexasTech University Health Science Center,Lubbock,TX.USA.Email:attilio.orazi@ttuhscedu1 EOSINOPHILIC DISORDERSeosinophilia associated with a hematopoietic neoplasm,eosinophilsoften bear the same molecular genetic aberrations as their progenitorsEosinophilia is defined as a PB eosino
