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Tumor Discovery Immunophenotypic patterns of childhood acute leukemia

(WHO). Hematopoietic neoplasm, or AL, exhibits immunophenotype. Children with inadequate/suboptimal
2
a heterogeneous molecular profile, requiring a more BMAs and unavailable flow cytometry findings were
precise diagnostic categorization and subcategorization. excluded from the study. All children confirmed with AL
2
Recent classifications of AL are more prognostic-oriented through flow cytometry were included in the study.
compared to older classification systems, as they are
based on immunophenotype, cytogenetics, and molecular 2.3. Immunophenotyping
typing. Proper classification is instrumental in enhancing Immunotyping through flow cytometry was conducted
3
patient management. 4 using the Cytomics FC 500 (Beckman Coulter, USA).
Immunophenotype-based classifications are more Peripheral blood and BMA samples were collected fresh
lineage-specific (B-cell ALL [B-ALL], T-cell ALL [T-ALL], in EDTA (ethylenediaminetetraacetic acid-anticoagulant)
and acute myeloid leukemia [AML]) and carry prognostic vials. The samples were analyzed within 24 h of collection.
significance. Therefore, this study has been conducted in For most of the cases, a pre-fixed panel of antibodies
specific regions of India. Recently, AL has been confirmed (CD34, HLA-DR, CD45, CD19, CD20, CD79a, CD10,
with immunophenotyping using flow cytometry. TdT, CD3, c-CD3, CD4, CD2, CD7, CD8, CD23,
Occasionally, the asynchronous expression of antigens or CD103, CD38, CD200, CD117, CD13, CD33, MPO,
antibodies on the cell surface is referred to as an aberrant CD64, CD11b, and CD15) was used in conjunction with
phenotype, such as the expression of T-cell lineage or B-cell fluorescein isothiocyanate (FITC [FL1), phycoerythrin
lineage markers in AML or the expression of myeloid (PE [FL2), ECD (FL3), and PC5 (FL5) dyes. The samples
lineage markers in T/B ALL. Certain cases cannot be were processed as per standard protocols for surface and
4
classified as ALL and AML based solely on morphology, cytoplasmic antibodies. Results were obtained by gating
cytochemistry, and immunohistochemistry. 5 This the blast cells with side scatter (SSC) versus forward scatter
phenomenon is due to the co-expression of lymphoid and followed by SSC versus CD45 gating.
myeloid immunophenotype markers on the cell surface, or AL, based on immunophenotype, was initially divided
the presence of two distinct cell populations. These cases into four groups and subsequently into subgroups.
6
are diagnosed with the availability of flow cytometry and Group 1 comprised B-ALL expressing CD19, c-CD79a,
are labeled as biphenotypic, hybrid, and mixed leukemia. 7
and c-CD22, along with variable CD34/HLA-DR, CD10,
The aim and objective of the present study are as CD24, and PAX5. Group 2 consisted of T-ALL expressing
follows: (i) to determine the immunophenotypic pattern TdT and variably expressing c-CD3, CD3, CD2, CD5, and
of childhood AL in Delhi-National Capital Region (NCR), CD7. Group 3 included AML, predominantly expressing
(ii) to provide the clinical and hematological profile of the MPO and variably expressing CD117, CD33, CD13, CD64,
immunophenotype of AL in children, and (iii) to correlate and CD15. Group 4 covered mixed phenotypic AL/aberrant
with prognostic outcomes. immunophenotypic AL antigens. All four groups were
correlated with their clinical details, hematological profiles,
2. Methods and prognostic outcomes.
2.1. Study design and data acquisition The aberrant immunophenotype was defined as the
This retrospective cross-sectional study was performed at a expression of surface antigen on a leukemic cell that
tertiary care institute in Delhi, India. Informed consent was differs from the normal maturation process of the cell
not applicable as the study was retrospective and involved lineage. While recent classifications of AL are based
4
no direct contact with patients. Data were retrieved from on molecular typing, the immunophenotype-based
the departmental archive. French–America–British (FAB) classification remains
robust for patient management. It was feasible for routine
2.2. Bone marrow aspirate (BMA) and trephine practice and cost-effective. The FAB classification includes
biopsy analysis
eight subtypes of AML (M0 – M7) and three subtypes of
Clinical data, BMA, and trephine biopsy slides of pediatric ALL (L1 – L3) (Table 1). 8
patients diagnosed with AL through bone marrow The 2016 WHO revised classification of leukemia is
aspiration, biopsy, and flow cytometry between January
2019 and June 2021 were analyzed. A total of 209 samples based on immunophenotypes and molecular characteristics
(Table 2).
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of BMA and biopsies were collected from 95 pediatric
patients with AL. Of these, 141 remission samples In addition, demographic profiles, clinical details,
were excluded, and a total of 68 patient samples were hemograms, and flow cytometry analyses of the patients
analyzed for clinical profile, hematological profile, and were noted.

Volume 3 Issue 2 (2024) 2 doi: 10.36922/td.2545