Abstract：
Malignant gastrointestinal neuroectodermal tumor (MGNET) is a sarcoma typically involving the gastrointestinal tract with neuroectodermal differentiation and EWSR1-ATF1/CREB1 fusions. Recently, rare MGNET cases were reported in extragastrointestinal sites. We identified 2 cases of MGNET arising in unprecedented laryngeal and intracranial locations, respectively. Both cases showed spindle and epithelioid tumor cells with amphophilic to clear cytoplasm and occasionally prominent nucleoli, arranged in solid, fascicular, and pseudoalveolar patterns. Case 1 exhibited moderate to marked nuclear atypia and focal intraepithelial component. In contrast, case 2 comprised predominantly low-grade epithelioid cells with extensive pseudopapillary structures. Both tumors showed an S100/SOX10-positive and HMB45/melan-A-negative immunoprofile as well as EWSR1-ATF1 fusion. A chief obstacle in diagnosing case 1 was the histologic and immunophenotypic resemblance to melanoma. The striking pseudopapillary architecture and the intracranial location of case 2 rendered differential diagnoses including meningioma and ependymoma. With the peculiar locations and morphology, these cases posed great diagnostic challenge.
摘要：
恶性胃肠道神经外胚层肿瘤（MGNET）是一种通常累及胃肠道的肉瘤，具有神经外胚层分化和EWSR1-ATF1/CREB1融合。最近,罕见的MGNET病例报道在胃肠外部位。我们确定了2例MGNET出现在前所未有的喉和颅内位置，分别。两例均显示梭形和上皮样肿瘤细胞，具有两亲性至透明的细胞质，偶尔有明显的核仁。固体排列，束状，和伪肺泡模式。病例1表现出中度至明显的核异型和局灶性上皮内成分。相比之下,病例2主要包括具有广泛假乳头结构的低度上皮样细胞。两种肿瘤均显示S100/SOX10阳性和HMB45/melan-A阴性免疫谱以及EWSR1-ATF1融合。诊断病例1的主要障碍是与黑色素瘤的组织学和免疫表型相似。病例2的惊人的假乳头结构和颅内位置可进行鉴别诊断，包括脑膜瘤和室管膜瘤。由于特殊的位置和形态，这些病例提出了巨大的诊断挑战。
