PMC10243748_01
Photomicrograph of the: A - bone marrow aspirate showing large and bizarre looking atypical cells with prominent nucleoli and deep basophilic cytoplasm (Giemsa stain; x400); B - some multinucleated forms are seen (Giemsa stain; x400). Inset showing dysmegakaryopoiesis; C and D - the trephine biopsy shows sheets of immature-appearing cells (C; H&E; x200) which are positive for E-cadherin immunostain (D; x400); E - CD34 is negative (x400); F - flow cytometry plot shows that these atypical cells express CD117 and CD235a.
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The aspirate showed the presence of large bizarre-looking atypical cells (~16% of all nucleated cells) with coarse chromatin, 2-5 prominent nucleoli, and deeply basophilic cytoplasm (Figure 1A). Occasional multinucleated forms were also noted (Figure 1B). Trephine biopsy was markedly hypercellular (cellularity 90-95%) with large immature cells, focally forming sheets, and scattered dysplastic megakaryocytes (Figure 1C). The immunohistochemistry performed on the trephine biopsy showed that the abnormal cells expressed E-cadherin (Figure 1D), but were negative for CD45, CD3, CD20, CD68, CD138, CD34 (Figure 1E), and MPO. Flow cytometry from the bone marrow aspirate revealed ~4.6% erythroid precursors showing abnormal maturation patterns, with co-expression of early-stage (CD117) and late (CD235a) erythroid markers (Figure 1F).