Coexistence of acute myeloid leukemia with a complex chromosomal translocation and monoclonal gammopathy of undetermined significance: A case report and literature review

Acute myeloid leukemia (AML) with chromosomal translocation t(8;21)(q22;q22.1) is a rare subtype, accounting for 4-8% of all cases of AML. Despite its rarity, it has a favorable outcome. The translocation event culminates in the formation of the Runt-related transcription factor 1 (RUNX1)::RUNX1 partner transcriptional co-repressor 1 (RUNX1T1) fusion protein, which is implicated in hematopoietic differentiation and maturation. Furthermore, monoclonal gammopathy of undetermined significance (MGUS) is characterized by the presence of monoclonal immunoglobulins in the blood or urine, serum M protein level of <3 g/dl and <10% clonal plasma cells in the bone marrow, with no accompanying end-organ damage associated with myeloma. The simultaneous occurrence of AML and MGUS is exceedingly rare. The present report describes the case of a male patient with AML and a RUNX1::RUNX1T1 fusion gene, not arising from the usual chromosomal translocation but rather from a complex translocation event involving t(8;17;21) (q22;q24;q22). The patient achieved complete remission (CR) following an idarubicin (12 mg/m², days 1-3) + cytarabine (100 mg/m², d1-7) regimen chemotherapy. Subsequent bone marrow monitoring revealed CR of AML during consolidation chemotherapy; however, ~5% of plasma cells were detected in the bone marrow. Flow cytology confirmed the presence of monoclonal plasma cells, and a positive hematuria immune-fixed electrophoresis assessment led to a diagnosis of MGUS. Due to economic constraints, the patient and their family declined high-dose cytarabine-based combination chemotherapy and hematopoietic stem cell transplantation, opting instead for intermittent use of standard doses of anthracycline combined with cytarabine maintenance therapy. The disease relapsed after 10 months, the patient discontinued treatment and died shortly after.