Complementary Role of Ancillary Tests in Acute Promyelocytic leukemia - A Case Series

Acute promyelocytic leukemia (APL) is a hematological emergency requiring prompt diagnosis and initiation of all-trans retinoic acid (ATRA) therapy to prevent life-threatening hemorrhage. While diagnosis is traditionally confirmed by identifying the t(15;17)(q24;q21) translocation or PML::RARα fusion, practical challenges-especially in resource-limited settings-necessitate an integrated, multimodal diagnostic approach. A retrospective analysis was conducted on seven APL cases diagnosed between 2022 and 2024. Diagnostic evaluation incorporated complete blood counts (CBC), peripheral smear and bone marrow morphology (MGG staining), cytochemistry (MPO, PAS), immunophenotyping by flow-cytometry, and molecular/cytogenetic confirmation via karyotyping, FISH, and RT-PCR. Cases were analyzed for morphological variants, test accessibility, and diagnostic concordance across modalities. The median patient age was 29 years (range: 13-70); 4 males and 3 females. Morphology revealed hypergranular (5/7) and hypogranular (2/7) variants. CBC scatterplots and strong MPO positivity supported initial diagnostic suspicion. Flow-cytometry typically showed a CD34-/HLA-DR - profile, with one atypical CD34+/HLA-DR + case. PML::RARα fusion was confirmed in 4/5 cases by FISH and in one FISH-negative case by RT-PCR (bcr3 variant). Karyotyping revealed t(15;17) in 4/4 cases, with additional trisomy 8 in two. Each modality contributed uniquely, with final diagnoses supported by at least two complementary methods in 6/7 cases. Morphological and scatterplot patterns are suggestive but may be ambiguous in hypogranular APL. Cytochemistry, flow-cytometry, and rapid molecular diagnostics (FISH, RT-PCR) are critical for timely confirmation. An integrated, stepwise diagnostic algorithm enhances accuracy and feasibility, especially in constrained settings, as demonstrated by our case series.

The online version contains supplementary material available at https://doi.org/10.1007/s12288-025-02258-7.