7094 Background: MYC, a transcription factor controlling DNA replication, is overexpressed in many cancers, yet rarely investigated in myeloid neoplasms, where its clinical significance is unknown. Objectives:Assess MYC expression by immunohistochemistry (IHC) in bone marrow (BM) of patients (pts) with acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), and acute promyelocytic leukemia (APL). Methods: MYC expression by IHC was assessed in BM of pts with AML, MDS, APL, and normal BM. MYC expression showed a distinct nuclear pattern. Cases were considered positive if > 5% blasts were stained. Results: We evaluated BM MYC expression in 220 pts during 2006-2013 (97 mo) with newly diagnosed AML (n=162), previously treated AML (induction failure or relapse) (n=30), MDS (n=19), and newly diagnosed APL (n=11). Median age was 60 yrs (13-88); 56% male. Normal BM (negative controls) showed negligible MYC expression (<5%, n=11). Varying degrees of MYC expression were observed in AML pts with median MYC expr...