Abstract
We describe a case of acute promyelocytic leukemia with circulating aberrant basophils. Recent studies have shown that basophilic differentiation is not uncommon in APL and likely under‐recognized in morphologic and immunophenotypic assessments.
Keywords: acute promyelocytic leukemia, basophils, flow cytometry, PML‐RARA
We describe a case of acute promyelocytic leukemia with circulating aberrant basophils. Recent studies have shown that basophilic differentiation is not uncommon in APL and likely under‐recognized in morphologic and immunophenotypic assessments.
1. INTRODUCTION
A 63‐year‐old woman presented to the emergency room with leg swelling and dyspnea and was diagnosed with deep venous thrombosis and bilateral pulmonary emboli. Complete blood count (CBC) revealed mild thrombocytopenia and neutropenia. She was treated with apixaban. A repeat CBC 1 month later revealed progressive thrombocytopenia (109 × 109/L) and neutropenia (0.5 × 109/L). Peripheral blood smear showed relatively increased atypical basophils (15%, 0.2 × 109/L) with hypogranulation/fine granulation (Figure 1, panels A‐B). Bone marrow assessment revealed 22% basophilic elements and 28% abnormal promyelocytes/blasts some with several Auer rods (Figure 1, panels C‐D). Flow cytometry confirmed distinct populations of promyelocytes/blasts (21%, CD45dim CD34‒ CD117++ CD33++ CD13+/‒ HLA‐Dr‒ CD11b‒ CD123‒/+ CD7‒) and basophils (15%, CD45mod CD34‒ CD117+/‒ CD33++ CD13++ HLA‐Dr‒ CD11b++ CD123+ CD7+/‒). Fluorescent in situ hybridization showed t(15;17)(q22;q12) in 44.5% of nuclei, suggesting that both subsets carry the translocation. Acute promyelocytic leukemia with PML‐RARA (APL) was diagnosed.
Figure 1.
A‐B, Peripheral blood smear (1000× magnification) displaying two atypical basophils with abnormal granulation. C‐D, Bone marrow aspirate smear (1000x magnification) showing promyelocytes/blasts with Auer rods (red arrowheads), other promyelocytes/blasts with or without cytoplasmic granulation, and immature and atypical basophils with abnormally coarse cytoplasmic granulation (blue arrows)
Basophilic differentiation of APL at presentation or after therapy is rarely reported.1 A recent study showed that basophilic traits of APL promyelocytes/blasts happen in up to one‐third of patients and are associated with increased risk of bleeding and worse survival,2 suggesting that such traits are under‐recognized by cytomorphology and flow cytometry.
CONFLICT OF INTEREST
Nothing to report.
AUTHOR CONTRIBUTIONS
AS: wrote the first draft of the paper, prepared the figure, and reviewed literature. KJ: revised the paper, included clinical information, and obtained patient consent.
Shameli A, Jamani K. Acute promyelocytic leukemia presenting with atypical basophils. Clin Case Rep. 2020;8:584–585. 10.1002/ccr3.2686
REFERENCES
- 1. Iwakiri R, Inokuchi K, Dan K, Nomura T. Marked basophilia in acute promyelocytic leukaemia treated with all‐trans retinoic acid: molecular analysis of the cell origin of the basophils. Br J Haematol. 1994;86:870‐872. [DOI] [PubMed] [Google Scholar]
- 2. Matarraz S, Leoz P, Fernandez C, et al. Basophil‐lineage commitment in acute promyelocytic leukemia predicts for severe bleeding after starting therapy. Mod Pathol. 2018;31:1318‐1331. [DOI] [PubMed] [Google Scholar]