Exploring mixed phenotype acute leukemia: Clinical, immunophenotypic, cytogenetic, and prognostic insights from a...

Mixed-phenotype acute leukemias (MPALs) are a rare and aggressive group of leukemias, accounting for approximately 2%-5% of all leukemia cases. MPAL is characterized by the expression of markers from more than one hematopoietic lineage, either myeloid and lymphoid, which can be identified through flow cytometry immunophenotyping. This study aims to describe the clinicopathological, immunophenotypic, and cytogenetic features of a cohort of 27 patients diagnosed with MPAL at our institution.

We conducted a retrospective analysis of 27 consecutive MPAL cases diagnosed between January 2016 and September 2020 at our tertiary care center. All cases were classified based on the WHO 2016 diagnostic criteria using flow cytometry for immunophenotyping. Available cytogenetic and molecular data were also analyzed.

Among 1622 acute leukemia cases diagnosed during the study period, 27 (1.7%) fulfilled the diagnostic criteria for MPAL. The cohort had a male-to-female ratio of 4.4:1, with a median age of 21 years. The cases were classified as B/myeloid (n = 16) and T/myeloid (n = 11). Cytogenetic data were available for 18 patients, of which 7 cases had a normal karyotype. The remaining cases displayed various abnormalities, including trisomy 8, t(8:14)(q11.2;q32), and t(9;22). The induction mortality rate was notably high at 54%, primarily due to infections and poor general condition of patients at presentation. No significant survival difference was observed between B/myeloid and T/myeloid subgroups.

MPAL remains a rare and challenging leukemia to diagnose and treat, requiring precise immunophenotypic analysis for accurate classification. MPAL constituted a small proportion (1.7%) of acute leukemias in our cohort and was associated with extremely poor outcomes, reflected by the very high induction mortality (54%) and median survival of only 1 month. Survival did not differ significantly between B/myeloid and T/myeloid subtypes, underscoring the uniformly adverse prognosis. These findings highlight the urgent need for improved supportive care, early recognition, and integration of novel strategies-including timely allogeneic transplantation-to improve outcomes in this clinically challenging and prognostically adverse entity.