CBFB::MYH11 Fusion Located on a Supernumerary Ring Chromosome 16 in Pediatric Acute Myeloid Leukemia: Diagnostic Challenges and Prognostic Implications

We report a unique pediatric acute myeloid leukemia (AML) case characterized by a <i>CBFB::MYH11</i> fusion located on a supernumerary ring chromosome 16. Following diagnosis through comprehensive blood and bone marrow assays, the patient was enrolled in the Children's Oncology Group (COG) study AAML1831 and randomized to the experimental treatment arm (Arm B). She received induction chemotherapy with CPX-351 (liposomal daunorubicin and cytarabine), gemtuzumab and ozogamicin (GO), and the cardioprotectant dexrazoxane and achieved complete remission (CR). The patient completed the treatment with sustained CR for 18 months. This case represents a rare cytogenetic phenomenon that is not well-documented in the current literature. Through a review of relevant publications, we contextualize this case within the spectrum of core binding factor AML (CBF-AML), highlighting diagnostic approaches, treatment strategies, and prognostic implications, particularly in cases involving atypical <i>CBFB::MYH11</i> fusions. The durable remission observed in this patient, despite the unusual cytogenetic presentation, provides valuable insights into therapeutic management. This report underscores the cytogenetic and molecular heterogeneity of <i>CBFB::MYH11</i> AML and emphasizes the importance of comprehensive genetic profiling using advanced techniques such as chromosomal microarray and next-generation sequencing.