Blast vacuolization in AML patients indicates adverse-risk AML and is associated with impaired survival after intensive induction chemotherapy

INTRODUCTION: Vacuolization is a frequently found morphological feature in acute myeloid leukemia (AML) blasts. Subcellular origin and biological function as well as prognostic impact are currently unknown. The aim of this study was to evaluate whether vacuolization correlates with clinically relevant AML features. MATERIALS & METHODS: Bone marrow smears of patients diagnosed with AML at the University Hospital Frankfurt between January 2011 and August 2013 were analyzed for blast vacuolization and correlated with clinically relevant AML features. Patients undergoing standard induction chemotherapy were further analyzed for molecular and cytogenetic features as well as treatment response and survival. RESULTS: 14 of 100 patients diagnosed with AML receiving standard induction chemotherapy had evidence of blast vacuolization. Positivity for vacuolization correlated with a CD15 positive immunophenotype and with a higher incidence of high-risk AML according to the European LeukemiaNet risk stratification. AML patients with blast vacuolization had a poor blast clearance after standard induction chemotherapy and poor survival. DISCUSSION: In conclusion, our findings demonstrate that vacuolization can easily be determined in myeloid leukemia blasts and may be a useful biomarker to predict AML risk groups as well as early treatment response rates and survival.