Ancient schwannoma is a rare retroperitoneal tumor that often remains asymptomatic and is frequently misdiagnosed. We present a case of a 16-year-old male with acute appendicitis, where a contrast-enhanced computed tomography scan incidentally revealed a well-defined cystic retroperitoneal lesion. The patient underwent appendectomy and enucleation of the mass. Histopathological analysis confirmed ancient schwannoma, showing Antoni A and B areas, degenerative changes, and positive S100 staining. Postoperative recovery was uneventful, with no recurrence at 6 months. This case underscores the importance of thorough imaging evaluations, even when assessing unrelated conditions, as incidental findings like ancient schwannoma can significantly impact patient management. Early diagnosis and complete surgical excision offer favorable outcomes.

Keywords: ancient schwannoma; appendicitis; case report; retroperitoneal tumor.

Published by Oxford University Press and JSCR Publishing Ltd. © The Author(s) 2025.

古施万细胞瘤是一种罕见的后腹膜肿瘤，常常无症状且经常被误诊。我们报告了一例16岁男性急性阑尾炎患者，在进行增强CT扫描时意外发现一个界限清楚的囊性后腹膜病变。该患者接受了阑尾切除术和肿物剥离手术。病理分析确认为古施万细胞瘤，表现为安托尼A区、安托尼B区、退行性变化以及S100染色阳性。术后恢复良好，在6个月随访中未见复发。此病例强调了在评估无关疾病时进行彻底影像学检查的重要性，因为像古施万细胞瘤这样的意外发现可能会显著影响患者的治疗管理。早期诊断和完全手术切除可获得良好的预后。

关键词： 古施万细胞瘤；阑尾炎；病例报告；后腹膜肿瘤。

由牛津大学出版社和JSCR出版有限公司发布。©作者 2025年。