Increased pDCs in a subset of AML. (A-B) Flow cytometric identification of pDCs (aqua population represents pDCs). (C) pDC proportion (percentage of white blood cells) in BM aspirates from patients with AML and normal controls (median ± IQR). AML, AML without pDC expansion; Controls, normal subjects; pDC-AML, AML with pDC expansion. (D) CD123 levels on CD34⁺ blasts and pDCs (median ± IQR). (E) Hematoxylin and eosin stain of BM biopsy from a representative patient with pDC-AML (inset: anti-CD34 immunostain). (F) Anti-CD123 immunostain of the patient from panel E. (G) Hematoxylin and eosin stain of BM biopsy from another representative patient with pDC-AML (inset: anti-CD34 immunostain). (H) Anti-CD123 immunostain of the patient in panel G. (I-J) Wright-Giemsa stain of flow-sorted leukemic blasts (I) and pDCs (J) from pDC-AML. **P < .01, ***P < .001. Original magnification, ×200 (E-H) and ×1000 (I-J). MFI, mean fluorescence intensity.