Introduction: Acute leukemias (AL) are a group of neoplastic disorders characterized by proliferation and accumulation of immature hematopoietic cells in peripheral blood (PB) and/or bone marrow (BM). This group of malignancies has varying clinical, morphologic, immunologic and molecular characteristics. AL displays characteristic patterns of antigen expression, which facilitate their identification and proper classification. AL are classified according to their commitment to either the myeloid or lymphoid lineage. Immunophenotyping has become very useful and reliable tool to diagnose and subtype acute leukemia precisely into different subtypes. Immunophenotyping can identify various intracellular and extracellular cell lineage specific markers and categorizes AL into Acute myeloid leukemia (AML), B cell acute lymphoid leukemia (B–ALL), T cell acute lymphoid leukemia (T–ALL) and Mixed Phenotypic Acute Leukemia (MPAL). Our study aimed to analyze Acute leukaemia immunophenotypically.

Methods: We prospectively investigated the phenotype of blast cells from 183 cases of acute leukemia patients using a large panel of monoclonal antibodies by multiparametric flowcytometry.

Results: 183 cases of acute leukemia were analyzed using multiparametric flowcytometry. Out of which 115 cases (62.84%) were Acute Myeloid Leukemia (AML), 49 cases (26.77%) were B cell Acute Lymphocytic Leukemia (B–ALL), 8 cases (4.37%) were T cell Acute Lymphocytic Leukemia (T–ALL) and 11 cases (6.01%) were Mixed Phenotypic Acute Leukemia (MPAL). 43/115 (37.4%) of AML cases, 16/49 (32.7%) of B–ALL cases and 6/8 (75.0%) of T–ALL cases demonstrated aberrant phenotype in our study. 38.26%, 6.08% and 1.7% cases of AML showed further lineage specific differentiation to monocytic, megakaryocytic and erythroid respectively. Most of the cases of megakaryocytic leukemia were from the paediatric age group.

Discussion: In view of the pitfalls in French American British (FAB) classification which was based on morphology, the World Health Organisation (WHO) classification emphasized the importance of immunophenotyping and defined the myeloid and lymphoid malignancies by the antigenic features of the neoplastic cells. Flowcytometry plays a major role in ALL patients to define therapeutically and prognostic groups such as B and T lineage ALL and to distinguish AML–M0 from ALL. Further, flowcytometry aid in diagnosing AML cases as well as defining different subgroups in AML. Thus immunophenotyping by flowcytometry not only helps in categorizing Acute leukemia but gives an immediate prompt diagnosis and providing help in accurate treatment.