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Abstract：
We report a case of primary intraabdominal ependymoma arising in the retropubic space of a male patient. An incidental intraabdominal mass was discovered in a 51-year-old man. Radiological studies revealed a 10 cm, solid and cystic tumor located in the Retzius fossa. Microscopically, the lesion was characterized by multiple cellular nodules composed of bland small cells forming true and pseudorosettes. No nuclear atypia, necrosis or increased mitotic activity was present. Neoplastic cells positive for AE1/3 and Cam5.2, and expressed patchy GFAP, and paranuclear dot-like to microvesicular EMA and D2-40, while S100, synaptophysin, PAX8, TLE1, WT1, inhibin, calretinin, Melan-A, and HMB45 were negative. Electron microscopy findings supported the diagnosis: 1) Frequent intracytoplasmic vacuoles with short and redundant microvilli and few cilia 2) lung intercellular junctions. The patient is alive with no evidence of disease for 4 years. Pathologists should be aware that rare extraneural ependymomas may occur in the Retzius space, even in a male patient. This entity should be kept in mind especially when the differential diagnosis is metastatic carcinoma with an unusual morphology and immune profile.
摘要：
我们报告了一例男性患者耻骨后间隙中出现的原发性腹内室管膜瘤。在一名51岁的男子中发现了一个偶然的腹内肿块。放射学研究显示10厘米，位于Retzius窝的实性和囊性肿瘤。微观上,病变的特征是多个细胞结节，由平淡的小细胞组成，形成真和假结球。没有核非典型，出现坏死或有丝分裂活性增加。肿瘤细胞AE1/3和Cam5.2阳性，表达斑片GFAP，核旁点状到微泡EMA和D2-40，而S100，突触素，PAX8,TLE1,WT1,抑制素,calretinin,Melan-A,HMB45为阴性。电子显微镜检查结果支持诊断：1）胞质内空泡频繁，微绒毛短而多余，纤毛少2）肺细胞间连接。患者存活4年，没有疾病迹象。病理学家应该意识到，罕见的神经外膜室管膜瘤可能发生在Retzius空间，即使是男性患者.尤其是当鉴别诊断是具有异常形态和免疫特征的转移性癌时，应牢记该实体。
