PMC10171747_01
Bone marrow trephine biopsy from the index case showing markedly increased cellularity for age with increased immature myeloid progenitors (blasts) admixed with dysplastic megakaryocytes with pleomorphic hyperchromatic nuclei (a). On immunohistochemistry, the blasts were strongly and diffusely positive for CD 34 (b), CD 117 (c), HLA-DR (not shown), and weakly positive for Myeloperoxidase (MPO) (not shown) comprising of 50% of marrow nucleated cells, thus consistent with a diagnosis of MPO positive AML. Also, the presence of clusters of dysplastic early erythroid progenitors as highlighted by E-cadherin immunostain (d) in this case
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F1
Organization [WHO]) and the presence of an increased population of myeloid blasts arranged in loose interstitial clusters and sheets (>50% of marrow nucleated cells) admixed with loosely clustered dysplastic early erythroid progenitors, and presence of dysplastic megakaryocytes (5-6/high power field) showing abnormal nuclear chromatin and small-cell morphology. On immunohistochemistry, the blasts were strongly and diffusely positive for CD 34, CD 117, Human Leukocyte Antigen - DR isotype, and weakly positive for myeloperoxidase, thus confirming the diagnosis of AML with myelodysplasia-related changes (WHO category II) as per the 2017 revised WHO classification (Figure 1a-d).