Ewing sarcoma (ES) is an uncommon mesenchymal neoplasm that typically develops as a bone mass, although up to 30% arise in extraskeletal sites. ES of the gastrointestinal (GI) and hepatobiliary tract is rare and may be misdiagnosed as other, more common neoplasms that occur in these sites. However, the correct classification of extraskeletal ES is important for timely clinical management and prognostication. We reviewed our experience of ES in the GI and hepatobiliary tract in order to further highlight the clinicopathologic features of these neoplasms and document the potential for misdiagnosis in this setting. The archives and consultation files of 6 academic institutions were retrospectively queried for cases of ES occurring in the GI and hepatobiliary tract. The histologic slides and ancillary studies were reviewed and clinical data were retrieved for each case through the electronic medical records, when available. Twenty-three patients with ES in the GI and/or hepatobiliary tract were identified from 2000 to 2022. Of these, 11 were women and 12 were men with a median age of 38 years (range, 2 to 64). Tumor locations included the pancreas (n=5), liver (n=2), stomach (n=3), colorectum (n=3), and small intestine (n=5), as well as tumors involving multiple organs, pelvis and retroperitoneum (n=5). Tumor size varied between 2 cm and 18 cm. Twenty were primary and 3 were metastases. Of the 23 cases, only 17% were initially diagnosed as ES. The most common misdiagnoses involved various forms of neuroendocrine neoplasia due to expression of synaptophysin and other neuroendocrine markers (22%). A wide variety of diagnoses including GI stromal tumor was considered due to aberrant CD117 expression (4%). The diagnosis of ES was ultimately confirmed by detection of the EWSR1 rearrangement in 22 cases. The remaining case was diagnosed using traditional immunohistochemistry. Follow-up information was available in 20 cases, with follow-up time varying between 2 and 256 months. Six patients with follow-up died of disease between 6 and 60 months following initial presentation. Our data indicate ES in the GI and hepatobiliary tract is commonly misdiagnosed leading to a delay in therapy. In light of the attendant therapeutic and prognostic implications, ES should be considered in the differential diagnosis of any GI or hepatobiliary tumor with epithelioid and/or small round cell morphology.

中文翻译：

---

胃肠道和肝胆道骨外尤文肉瘤：欺骗性免疫表型通常导致误诊。


尤文肉瘤 (ES) 是一种罕见的间叶性肿瘤，通常以骨块形式发育，但高达 30% 的肿瘤发生在骨骼外部位。胃肠道 (GI) 和肝胆道的 ES 很少见，可能会被误诊为发生在这些部位的其他更常见的肿瘤。然而，骨外ES的正确分类对于及时的临床管理和预后非常重要。我们回顾了胃肠道和肝胆道 ES 的经验，以进一步强调这些肿瘤的临床病理特征，并记录在这种情况下误诊的可能性。回顾性查询6个学术机构的档案和会诊档案，了解发生于胃肠道和肝胆道的ES病例。对组织学切片和辅助研究进行了审查，并通过电子病历（如果有）检索了每个病例的临床数据。 2000 年至 2022 年间，共鉴定出 23 名胃肠道和/或肝胆道 ES 患者。其中，11 名女性和 12 名男性，中位年龄为 38 岁（范围为 2 至 64 岁）。肿瘤部位包括胰腺（n=5）、肝脏（n=2）、胃（n=3）、结直肠（n=3）和小肠（n=5），以及涉及多个器官、盆腔的肿瘤和腹膜后（n=5）。肿瘤大小在2厘米至18厘米之间。 20 个是原发灶，3 个是转移灶。在这 23 例病例中，只有 17% 最初被诊断为 ES。最常见的误诊涉及由于突触素和其他神经内分泌标记物表达而导致的各种形式的神经内分泌肿瘤（22%）。由于 CD117 表达异常 (4%)，多种诊断被考虑，包括胃肠道间质瘤。 ES的诊断最终通过检测22例EWSR1重排得到证实。剩下的病例是使用传统的免疫组织化学诊断的。 20 例有随访信息，随访时间在 2 至 256 个月之间。 6 名随访患者在初次就诊后 6 至 60 个月内死于疾病。我们的数据表明，胃肠道和肝胆道的 ES 通常被误诊，导致治疗延迟。鉴于随之而来的治疗和预后影响，在任何具有上皮样和/或小圆形细胞形态的胃肠道或肝胆肿瘤的鉴别诊断中应考虑 ES。