Flow Cytometric Immunophenotyping of Mixed Phenotype Acute Leukemia in a Tertiary Care Hospital of Eastern Odisha

<b>Background:</b> Acute lymphoblastic leukemia affects both adults and children. Mixed phenotype acute leukemia (MPAL) is a rare subset featuring blasts with multiple lineage-specific antigens. Diagnosis is made via flow cytometric immunophenotyping with specific CD markers. This study aims to correlate MPAL's incidence, hematological findings, clinical profiles, and immunophenotypic features with treatment outcomes and prognostic significance. <b>Materials and Methods:</b> A total of 750 cases of acute leukemia involving pediatric and adult patients were examined at SCB Medical College and Hospital in Cuttack, Odisha. Based on the WHO 2008 criteria, twenty-nine cases of MPAL were identified using morphological, cytochemical, and immunophenotypic features. The study covered all age groups admitted to the Department of Hematology from September 2011 to April 2021. <b>Results:</b> Flow cytometric analysis of 750 cases showed B lymphoblastic leukemia as the most common subtype. Of the 29 MPAL cases (3.86%), 15 were B/myeloid, 13 T/myeloid, and one B/T/myeloid. Twenty-three cases received induction chemotherapy, with 12 achieving complete remission. The median survival was 11months, with a 15-month survival rate of 39%. Pediatric patients had a 60% survival rate at 15 months, compared to 30% for adults. <b>Conclusion</b>: MPAL is a rare acute leukemia diagnosed through flow cytometry. Prognostic factors include age at onset, CD34 negativity, HLA-DR presence, BCR-ABL fusion, and MLL rearrangement, which indicate a poor prognosis. Children tend to have better outcomes and complete remission than adults, with therapies for ALL being more effective than those for acute myeloblastic leukemia.