Discrepancy In Bone Marrow Blast Counts Between Morphology And Flow Cytometry And Its Potential Clinical Implications.

e18031 Background: Both bone marrow morphology (MO) and flow cytometry (FC) are traditionally used in characterizing the blast percentage (BP) in patients with newly diagnosed acute myeloid leukemia (AML). We examined how often the 2 methods were discordant in assessing BP, covariates associated with these discrepancies, and whether discrepancies were an independent predictor of outcome. Methods: We reviewed 310 newly diagnosed AML patients that were treated at SCCA/FHCRC from January 2008 to December 2013. We categorized patients as (a) BP by MO > 10% (absolute) higher than BP by FC, (b) BP by FC > 10% absolute than BP by MO,or (c) BP by MO and FC within 10% of each other. We did the same using cutoffs of 20% and 5%, as well as > 1 standard deviation (SD) above or below the regression line. Since the blast percentage reported by flow cytometry is based on the total white blood cells after lysis of erythroid component, we corrected the blast percentage by morphology for the erythroid cells counted. Covari...