A 5-year-old male child was diagnosed with interdigitating dendritic cell sarcoma (IDCS) during his maintenance therapy for B-cell precursor acute lymphoblastic leukemia (B-ALL). Multiplex lymph node involvements of the neck were found by positron emission tomography CT (PET-CT). Treatments, including surgical and chemotherapy, resulted in complete remission. Four years later, systemic bone infiltration was discovered. Surgical resection of the IV rib and intensive chemotherapy led to a complete morphological remission, and allogeneic bone marrow transplantation was performed. Comprehensive genomic profiling of the formalin fixed the tumor tissue, and the cryopreserved leukemic cells revealed several common alterations and divergent clonal evolution with a novel MAP2K1 mutation of the IDCS, which is responsible for the trans-differentiation of the common lymphoid-committed tumor progenitor.

一名 5 岁男童在 B 细胞前体急性淋巴细胞白血病 (B-ALL) 维持治疗期间被诊断出患有交叉指状树突细胞肉瘤 (IDCS)。正电子发射断层扫描CT（PET-CT）发现颈部多处淋巴结受累。治疗，包括手术和化疗，导致完全缓解。四年后，发现全身骨浸润。IV 肋骨的手术切除和强化化疗导致形态学完全缓解，并进行了异体骨髓移植。福尔马林的全面基因组分析固定了肿瘤组织，冷冻保存的白血病细胞揭示了几种常见的改变和不同的克隆进化MAP2K1IDCS 的突变，它负责常见的淋巴定向肿瘤祖细胞的转分化。