Acute myeloid leukemia with t(16;21)(q24;q22), CBFA2T3::RUNX1, in post-treatment setting, a case report

Abstract

Abstract Introduction/Objective Acute myeloid leukemia (AML) with t(16;21)(q24;q22), CBFA2T3::RUNX1 is an uncommon entity that has been reported in both pediatric and adult patients as de novo AML or secondary to prior chemo/radiation therapy. CBFA2T3::RUNX1 AMLs share similar clinico-pathological features and gene expression profile with RUNX1::RUNX1T1 AML. Methods/Case Report We report a case of AML with CBFA2T3::RUNX1 in a 52 year old female who had history of small cell cervical cancer treated with chemotherapy (4 cycles of cisplatin and etoposide) and pelvic radiation therapy. About 17 months after completion of therapy, she presented with anemia and thrombocytopenia, normal WBC/neutrophil count, eosinophilia and increased blasts (up to 10%) in blood. Bone marrow biopsy shows AML with maturation (FAB-M2), erythropoiesis is present, whereas megakaryocytes are decreased. Flow cytometry analysis shows myeloblasts with aberrant CD19 and CD56 expression; in addition, increased CD117/tryptase positive cells are noted, mostly interstitial and more concentrated around bone trabeculae. By immunohistochemical stains, these cells are at least partially positive for CD25, negative CD2, CD30. Karyotype studies demonstrate t(16;21)(q24;q22) and trisomy 8 in all metaphases. FoundationOne heme NGS studies confirmed CBFA2T3::RUNX1 fusion, and no additional mutations were identified. Patient received induction chemotherapy with Idarubicin/Cytarabine plus GO (Gemtuzumab ozogamicin); day 14 bone marrow showed chemotherapeutic effect and she is now in morphologic remission 5 months after diagnosis. Results (if a Case Study enter NA) NA Conclusion Our case adds to the limited knowledge of CBFA2T3::RUNX1 AMLs. Our case shows morphological and immunophenotypic features similar to AML with RUNX1::RUNX1T1, with unusual presentation of peripheral eosinophilia, and increased CD117/tryptase positive cells in bone marrow, the latter has been reported occasionally in core binding factor AMLs. We emphasize the importance of comprehensive genetic studies in AML patients, lack of adverse genetic abnormalities in our patient indicates favorable risk category regardless of the post-treatment clinical setting.