The PLEKHH2::ALK fusion is a rarely reported gene fusion identified predominantly in lung adenocarcinomas. Tumors with this fusion have been reported to be of durable response to ALK inhibitors. We herein present the case of a 21-year-old woman with a histomorphologically heterogenous mesenchymal neoplasm of the pelvis, expressing both s100 and CD34, with subsequently identified PLEKHH2::ALK fusion. To our knowledge, only a single mesenchymal neoplasm with this gene fusion has been previously reported. We propose that this tumor represents one with a novel ALK fusion in the emerging family of s100 and CD34 expressing mesenchymal neoplasms with oncogenic kinase alterations akin to NTRK-rearranged mesenchymal neoplasms, rather than inflammatory myofibroblastic tumor. Importantly, this tumor demonstrated a significant response to the ALK inhibitor brigatinib.

PLEKHH2 ::ALK融合是一种很少报道的基因融合，主要在肺腺癌中发现。据报道，具有这种融合的肿瘤对 ALK 抑制剂具有持久的反应。我们在此介绍一名 21 岁女性的病例，她患有骨盆组织形态学异质性间充质肿瘤，同时表达 s100 和 CD34，随后发现PLEKHH2::ALK融合。据我们所知，以前只报道过一种具有这种基因融合的间充质肿瘤。我们认为该肿瘤代表一种在新兴的 s100 和 CD34 表达间充质肿瘤家族中具有新型ALK融合的肿瘤，具有类似于NTRK的致癌激酶改变-重排的间充质肿瘤，而不是炎性肌纤维母细胞肿瘤。重要的是，该肿瘤表现出对 ALK 抑制剂布加替尼的显着反应。