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Key Words: AML; Cytogenetics; Recurrent abnormalities
Am J Clin Pathol July 2015;144:6-18
DOI: 10.1309/AJCPI9C8UILYQTNS
ABSTRACT
Objectives: Session 1 of the 2013 Society for Hematopathology/European Association for Hematopathology Workshop was devoted to the cases of acute myeloid leukemia (AML) with recurrent cytogenetic abnormalities.
Methods: Based on World Health Organization 2008 criteria, seven specific translocations are defined as "recurrent" in AML. Of these seven, three are considered to be AML defining regardless of blast percentage. Workshop cases provided the opportunity to consider potential new AML-defining cytogenetic mutations, as well as other unique aspects of AML with cytogenetic abnormalities.
Results: Most of the 38 cases submitted were acute promyelocytic leukemia (APL) with t(15;17)(q24.1;q21.1) and so-called variants (12 cases), AML with t(8;21)(q22;q22) (seven cases), AML with inv(3)(q11q26.2) (six cases), and AML with 11q23 translocations (five cases).
Conclusions: This review focuses on providing updated recommendations for the rapid diagnosis of APL, discussing the types and significance of variant RARA mutations in APL-like leukemias, and refining low-blast-count (oligoblastic) AML. In addition, the significance of unique morphologic, immunophenotypic, and genetic variations in AML defined by a recurrent cytogenetic abnormality is included.
The 2008 World Health Organization (WHO) classification system for acute myeloid leukemia (AML) includes seven types of AML with recurrent cytogenetic abnormalities, of which only three are AML defining-that is, the detection of t(8;21)(q22;q22), inv(16)(p13.1q22)/t(16;16)(p13.1;q22), or t(15;17)(q24.1;q21.1) warrants a diagnosis of AML regardless of the blast percentage ?Table 1?.1 The four other AML subtypes with recurrent cytogenetic abnormalities are not specific for AML, although t(1;22)(p13;q13) is highly specific for acute megakaryoblastic leukemia in children and is therefore essentially AML defining (Table 1).1
Session 1 Workshop Cases
Thirty-eight cases with recurrent cytogenetic abnormalities were assigned to session 1. The case number, consensus diagnosis, and unique features of these 38 cases are summarized in ?Table 2?. As with all workshops, these cases represent more unique AMLs with various distinctive features, including cryptic fluorescence in situ hybridization (FISH) and cytogenetics, unique three-way and other variant translocations, and rare cytogenetic subtypes of AML. This workshop summary incorporates not only the unique aspects of these workshop cases but also standard day-to-day approaches for AML diagnosis and subclassification.
Acute Promyelocytic Leukemia
Among the subtypes of AML with recurrent cytogenetic abnormalities, acute promyelocytic leukemia (APL) is...