Morphologic & molecular characteristics of de novo AML With JAK2 V617F mutation

Background: JAK2 V617F mutation (mut) in acute myeloid leukemia (AML) is rare. We describe the clinicopathologic findings of a singleinstitution series of 11 de novo AML cases with JAK2 V617. Methods: We identified cases of de novo AML with JAK2 V617F over a 10-year period. We reviewed diagnostic peripheral blood and bone marrow (BM) morphologic, cytogenetic, and molecular studies, including nextgeneration sequencing. The control group consisted of 12 patients with JAK2 wild-type (wt) AML matched for age, sex, and diagnosis. Results: We identified 11 patients (0.5%) with JAK2 V617F, with a median age at diagnosis of 72.5 years (range, 36-90 years). Ten neoplasms were classified as AML with myelodysplasia-related changes and 1 as AML with t(8;21)(q22;q22). All JAK2mut AML cases showed at least bilineage dysplasia, 7 of 11 showed fibrosis, 8 of 11 had an abnormal karyotype, and 5 had deletions or monosomy of chromosomes 5 and 7. Using the European LeukemiaNet (ELN) classification, 9 patients (82%) with JAK2mut AML were intermediate-2 and adverse risk. Cases of JAK2mut AML did not have mutations in other activating signaling pathways (P=.013); 7 (64%) showed additional mutations in at least one gene involving DNA methylation and/or epigenetic modification. Patients with JAK2mut AML had a significantly higher median BM granulocyte percentage (12% vs 3.5%; P=.006) and a higher frequency of ELN intermediate-2 and adverse risk cytogenetics (P=.04) compared with those with JAK2wt AML. JAK2mut AML showed higher circulating blasts, but this difference was not significant (17% vs 5.5%; P=not significant). No difference was seen in the median overall survival rate of patients with JAK2mut AML versus those with JAK2wt AML (14 vs 13.5 months, respectively). Conclusions: De novo JAK2mut AML is rare and frequently found in patients with dysplasia, BM fibrosis, and abnormal karyotype with intermediate- or high-risk features; gene mutations in DNA methylation and epigenetic-modifying pathways; and absence of gene mutations in activating signaling pathways.