Chronic myelomonocytic leukemia (CMML) is a rare malignant neoplasm of the blood-forming cells in bone marrow characterized by persistent monocytosis. Although most patients with CMML show clonal genetic aberrations, there is no known cytogenetic or molecular genetic finding that is specific to CMML. We report a patient who had a clinical and morphological presentation consistent with CMML. The genetic work-up showed an ETV6-ABL1 fusion consequent to a 9;12 translocation, and a missense mutation in SMC1A (c.1757G>A, p.Arg586Gln). The SMC1A mutations are recurrent, albeit rare, in myeloid malignancies, without an established clinical significance in CMML. ETV6-ABL1 fusion is a rare but recurrent genetic aberration found in various hematologic malignancies involving both the lymphoid and myeloid lineage, but to the best of our knowledge, CMML is an exceptionally rare presentation of ETV6-ABL1 rearranged neoplasm. ETV6-ABL1 fusion is often formed through complex rearrangements, and usually cryptic by routine G-banded chromosome analysis. The diseases associated with this rearrangement generally have an aggressive course, hence detecting or excluding this rearrangement during diagnostic work-up is critical for treatment planning.

慢性粒细胞性单核细胞白血病（CMML）是骨髓中罕见的恶性肿瘤，其特征在于持续性单核细胞增多症。尽管大多数CMML患者表现出克隆遗传畸变，但尚无特定于CMML的已知细胞遗传学或分子遗传学发现。我们报告了一名患者，其临床表现和形态学表现与CMML一致。遗传检查显示，ETV6-ABL1融合导致9:12易位，并且SMC1A中发生错义突变（c.1757G> A，p.Arg586Gln）。该SMC1A突变是反复发作，尽管罕见，在髓系恶性肿瘤，在不CMML建立的临床意义。ETV6-ABL1融合是在涉及淋巴样和髓样谱系的各种血液系统恶性肿瘤中发现的罕见但反复出现的基因畸变，但是据我们所知，CMML是ETV6-ABL1重排肿瘤的一种罕见的表现。ETV6-ABL1融合通常是通过复杂的重排形成的，并且通常通过常规的G带染色体分析进行隐秘的形成。与这种重排相关的疾病通常具有侵袭性病程，因此在诊断检查期间检测或排除这种重排对于治疗计划至关重要。