Myelodysplastic syndrome with t(6;9)(p22;q34.1) categorized as acute myeloid leukemia: A large multicenter study of 105 cases

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Conference Proceeding

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Modern Pathology


Background: The t(6;9)(p23;q34.1)/DEK-NUP214 is a recurrent genetic abnormality that occurs in a subset of cases of acute myeloid subset leukemia (AML) and rarely in myelodysplastic syndrome (MDS). However, it is not known whether all cases with t(6;9) (p23;q34.1) should be categorized as AML when blast count is <20%. In this study, we characterized and compared the clinicopathologic features of patients with MDS versus AML harboring t(6;9)(p23;q34.1). Design: Cases of AML or MDS carrying t(6;9)(p23;q34.1), diagnosed in 10 institutions, were collected and their clinicopathologic features were reviewed retrospectively. Results: The study cohort included 105 patients with t(6;9): 75 patients with AML and 30 with MDS. In all 98 patients with available data, the t(6;9) was detected at initial diagnosis of AML or MDS. There were 53 men and 52 women with a median age of 44 years (range, 10- 82) at initial diagnosis. Patients with AML were slightly younger than patients with MDS (median: 39 vs. 52 years) but this difference was not significant (P=0.08). As expected, patients with AML presented with leukocytosis and higher blast counts in peripheral blood and bone marrow (P=0.009, 0.004, <0.0001, respectively). However, no significant differences were observed in the hemoglobin level, platelet count, and basophil percentages in peripheral blood and bone marrow between patients with MDS versus AML. The median follow up time was 21.8 months. Of 30 patients with MDS, 17 (57%) developed AML after a median interval of 29 months (range, 1-94). There was no difference in overall survival between patients with MDS versus AML (median: 33.9 vs. 23.7 months, P=0.45). Fifty-seven patients received stem cell transplant during their clinical course. Patients who received transplant had longer overall survival than the non-transplant group (median: not reached vs. 17.3 months, P<.0001). After stratification by status of transplant, however, there were no significant differences between patients with MDS and patients with AML. Conclusions: Our data support the idea that myeloid neoplasms associated with t(6;9), irrespective of blast percentage, are best categorized as acute myeloid leukemia with recurrent genetic abnormalities, analogous to the WHO classification guidelines for myeloid neoplasms with t(8;21) and inv(16). Aggressive treatment strategies such as stem cell transplant might improve the survival of patients with myeloid neoplasms associated with t(6;9).





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