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Frequent RUNX1 mutations in acute leukemia + pDC
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Figure 1. Morphologies and immunophenotypes of populations of interest. (A to C) Representative morphologic aspects of peripheral blood smears from patient N1 (magnification 1,000X). (A) Blast cells are medium sized with a high nuclear cytoplasmic ratio, fine chromatin with proeminent nucleoli. Cytoplasm is basophilic with some rare azurophilic granulations. (B) Plasmacytoid dendritic cells (pDC) are smaller with more mature chromatin. The cytoplasm is less basophilic without granu- lation but sometimes pseudopodia and small vacuoles under the cytoplasmic membrane. (C) A blast cell (top), a pDC with pseudopodia (center) and a monocyte (bot- tom). (D to E) Representative immunophenotype after gating on FSC-A vs. FSC-H plus sides catter (SSC) vs. forward scatter (FSC) to select singlets, leucocytes and exclude debris (not shown). Lymphocytes in blue (CD45bright/SSCdim cells); immature blasts in black (CD34+ cells); pDC in pink (CD123bright); monocytes in green (CD123dim, CD33bright, CD64bright); cDC in orange (CD123+, CD33+ CD64dim). (D) Patient N8: acute myeloid leukemia with minimal differentiation (M0-AML) with a con- tinuum of phenotypic acquisition of markers (arrows) from the immature blasts: downregulation of CD13 and CD33 to pDC or upregulation to monocytes and cDC; downregulation of CD117 and CD34 to pDC/monocytes/cDC. (E) Patient N12: M0-AML with Tdt+, HLA-DRbright, CD33-, cCD13+ immature blasts; CD7+ CD4+ CD56– pDC.
for normally distributed variables or the c2 test with Yates’ conti- nuity correction for categorical variables. Correlations between quantitative variables were investigated by linear regression analy- ses. All statistical tests were two-sided, with a 5% alpha risk. Results are expressed as median (range). For further details see the Online Supplementary Appendix.
Results
Patients
Fifteen patients were included, mainly elderly men with a median age of 70 years (range, 52-87) and a sex ratio of
4:1 (Table 1). Cytological analysis of BM aspiration, asso- ciated with phenotypic data, found 11 cases of AML with minimal differentiation (M0-AML in French-American- British [FAB] classification) with a prior history of cytope- nia in one of them; one AML without maturation (AML- 1); two acute myelomonocytic leukemia (M4-AML) with a prior history of CMML; and one M5-AML secondary to another myelodysplastic syndrome/myeloproliferative neoplasm (MDS/MPN) analyzed during progression under induction treatment. On BM aspiration, blast cells were observed in all cases, associated with pDC, described as smaller with a more mature chromatin, faint basophilic cytoplasm without granulation, sometimes small vacuoles
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