MLL-ELL融合基因是各种MLL融合基因中的罕见情况。我们首次报道了一例成人MLL-ELL阳性急性髓系白血病的唯一表现为骨髓肉瘤。我们报告了一例33岁男性患者，于2022年6月入院，右枕区出现大约7 cm × 8 cm的肿块。血液检查正常。患者进行了右枕部巨大皮下肿块切除和切口瓢状皮瓣移植手术。免疫组织化学结果对过氧化物酶、CD43和CD45呈阳性，对CD3、CD20、CD34和CD56呈阴性。骨髓穿刺检查显示细胞过多，髓母细胞占20%。流式细胞术显示髓母细胞占核细胞的27.21%，表达CD33、CD38和CD117。核型为46, XY, t (11, 19) (q23; p13.1), -12, + mar/46, XY。下一代测序显示MLL第7外显子与ELL第2外显子融合。最终诊断为MLL-ELL阳性的急性髓系白血病(M2亚型)合并皮下骨髓肉瘤。MLL-ELL阳性急性髓系白血病合并皮下骨髓肉瘤是一种罕见的临床实体。需要进一步研究揭示皮下骨髓肉瘤发病机制的分子机制。©作者2023. Baishideng Publishing Group Inc. 版权所有.

The mixed lineage leukemia (MLL)-eleven-nineteen lysine-rich leukemia (ELL) fusion gene is a rare occurrence among the various MLL fusion genes. We present the first case in which myeloid sarcoma (MS) was the only manifestation of adult MLL-ELL-positive acute myeloid leukemia (AML).We report a case of a 33-year-old male patient who was admitted in June 2022 with a right occipital area mass measuring approximately 7 cm × 8 cm. Blood work was normal. The patient underwent right occipital giant subscalp mass excision and incisional flap grafting. Immunohistochemistry was positive for myeloperoxidase, CD43 and CD45 and negative for CD3, CD20, CD34, and CD56. The bone marrow aspirate showed hypercellularity with 20% myeloblasts. Flow cytometry showed that myeloblasts accounted for 27.21% of the nucleated cells, which expressed CD33, CD38, and CD117. The karyotype was 46, XY, t (11, 19) (q23; p13.1), -12, + mar/46, XY. Next-generation sequencing showed a fusion of MLL exon 7 to exon 2 of ELL. A diagnosis of MLL-ELL-positive AML (M2 subtype) with subcutaneous MS was made.MLL-ELL-positive AML with MS is a rare clinical entity. Additional research is needed to elucidate the molecular mechanisms of the pathogenesis of MS.©The Author(s) 2023. Published by Baishideng Publishing Group Inc. All rights reserved.