Abstract：
Malignant gastrointestinal neuroectodermal tumors (GNETs) are mesenchymal tumors that typically arise in the digestive tract and harbor EWSR1::ATF1 or EWSR1::CREB1 fusions. We report a case of primary retroperitoneal GNET in a 38-year-old woman who presented with a month-long fever with increased serum IL-6 level. A right retroperitoneal mass of 7 cm consisting of diffuse sheets of small cells with a high nuclear-to-cytoplasmic ratio and scattered osteoclast-like multinucleated giant cells was confirmed apart from the digestive tract. Peripheral lymphoid cuff and focal pseudoangiomatous spaces were present, reminiscent of angiomatoid fibrous histiocytoma. The tumor cells were positive for S100 protein and SOX10 and negative for melanocytic markers. Fluorescent in situ hybridization revealed EWSR1 and CREM gene rearrangements, consistent with EWSR1::CREM fusion, which has never been reported in GNET. The patient lives with recurrent lesions for 8 months. This case was associated with several unusual features and contributes to the evolving GNET concept.
摘要：
恶性胃肠道神经外胚层肿瘤（GNETs）是通常出现在消化道中的间充质肿瘤，并带有EWSR1::ATF1或EWSR1::CREB1融合。我们报告了一名38岁女性原发性腹膜后GNET的病例，该女性患有一个月的发烧，血清IL-6水平升高。除消化道外，还确认了一个7厘米的右腹膜后肿块，其中包括具有高核-细胞质比的小细胞弥散片和分散的破骨细胞样多核巨细胞。存在外周淋巴袖套和局灶性假性血管瘤腔，让人想起血管瘤样纤维组织细胞瘤。肿瘤细胞S100蛋白和SOX10阳性，黑素细胞标记阴性。荧光原位杂交显示EWSR1和CREM基因重排，与EWSR1::CREM融合一致，GNET中从未报道过。患者复发病变8个月。这种情况与几个不寻常的功能有关，并有助于不断发展的GNET概念。
