Gündoğdu Fatma, Agaimy Abbas, Aytaç Selin, Hazar Volkan, Üner Ayşegül, Kösemehmetoğlu Kemal
Department of Pathology, Hacettepe University Faculty of Medicine, Ankara, Türkiye.
Department of Pathology, Erlangen University, Erlangen, Germany.
Virchows Arch. 2025 Feb;486(2):405-410. doi: 10.1007/s00428-024-03766-z. Epub 2024 Feb 20.
Extramedullary involvement of acute myeloid leukemia (AML), aka myeloid sarcoma, is a rare phenomenon in acute megakaryoblastic leukemia with RBM15:: MRTFA(MKL1) fusion, which might mimic non-hematologic malignancies. A 7-month-old infant presented with leukocytosis, hepatosplenomegaly, multiple lymphadenopathies, and a solid mass in the right thigh. Initially, the patient was diagnosed with a malignant vascular tumor regarding the expression of vascular markers from the biopsy of the right thigh lesion that was performed after the inconclusive bone marrow biopsy. The second bone marrow biopsy, which was performed due to the partial response to sarcoma treatment, showed hypercellular bone marrow with CD34 and CD61-positive spindle cell infiltration and > 20% basophilic blasts with cytoplasmic blebs. RNA sequencing of soft tissue biopsy revealed the presence of RBM15::MRTFA(MKL1) fusion. Based on these findings, myeloid sarcoma/AML with RBM15::MRTFA(MKL1) fusion diagnosis was made. AML with RBM15::MRTFA(MKL1) fusion can initially present as extramedullary lesions and might cause misdiagnosis of non-hematologic malignancies.
急性髓系白血病（AML）的髓外浸润，即髓肉瘤，在伴有RBM15::MRTFA（MKL1）融合的急性巨核细胞白血病中是一种罕见现象，它可能会被误诊为非血液系统恶性肿瘤。一名7个月大的婴儿出现白细胞增多、肝脾肿大、多处淋巴结肿大以及右大腿有一个实性肿块。最初，在骨髓活检结果不明确后，对右大腿病变进行活检，根据血管标志物的表达，患者被诊断为恶性血管肿瘤。由于对肉瘤治疗有部分反应而进行的第二次骨髓活检显示骨髓细胞增多，有CD34和CD61阳性的梭形细胞浸润，以及>20%的嗜碱性母细胞伴有胞质小泡。软组织活检的RNA测序显示存在RBM15::MRTFA（MKL1）融合。基于这些发现，做出了伴有RBM15::MRTFA（MKL1）融合的髓肉瘤/AML的诊断。伴有RBM15::MRTFA（MKL1）融合的AML最初可能表现为髓外病变，并可能导致非血液系统恶性肿瘤的误诊。
