Ott_a_217622 6157..6163

*These authors contributed equally to this work Background: Acute promyelocytic leukemia (APL) is commonly characterized by the fusion of retinoic acid receptor alpha (RARA) with promyelocytic leukemia (PML). Most APL patients acquire long-term survival after treatment with all-trans retinoic acid (ATRA) or arsenic agents-based chemotherapy. Case presentation: A rare case of APL was reported after IRF2BP2-RARA was detected in the relapsed process using next-generation RNA-sequencing analysis. In addition, the mutation of NRAS was also detected. ATRA and arsenic trioxide combined with daunorubicin were used during induction treatment. The patient acquired complete remission but relapsed in 12 months. The patient was resistant to all other chemotherapies and refused any further therapy. The literature review indicated that allogeneic hematopoietic stem cell transplantation might be a therapeutic method to treat APL with IRF2BP2-RARA fusion. Conclusion: Atypical APL should be considered even if the patients present with normal chromosomal karyotype and no classic PML-RARA fusions, but classical clinical features and bone marrow cell morphology. We reported a case of APL with IRF2BP2-RARA fusion was shown to harbor the NRAS mutation at relapse.