Mixed phenotype acute leukemia of B-cell and T-cell lymphoblastic lineage: A rare presentation of a rarest phenotype - A case report

Mixed phenotype acute leukemia (MPAL) is recognized as a rare form of leukemia, with an incidence rate of <2–3%. The prevalent subtypes include B-cell and myeloid and T-cell and myeloid, while B-cell and T-cell and trilineage MPAL are exceedingly uncommon. We report a case involving a 23-year-old male who presented with acute leukemia but exhibited no peripheral cytopenias. Flow cytometry and immunohistochemistry revealed a singular population of blasts that expressed markers for both B-cell and T-cell lineages. Initially, the patient was treated using the augmented Berlin-Frankfurt-Münster protocol; however, there was no peripheral clearance of blasts observed on Day 7, and the bone marrow did not achieve remission by Day 35 following therapy.