Clinical Laboratory, University of Miyazaki Hospital, 5200 Kihara, Kiyotake, Miyazaki, Miyazaki, 889-1692, Japan.
Section of Oncopathology and Regenerative Biology, Department of Pathology, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan.
J Med Case Rep. 2022 Aug 20;16(1):312. doi: 10.1186/s13256-022-03555-9.
Dura-attached supratentorial extra-axial ependymoma is a very rare type of tumor, with only nine reported cases. Preoperative diagnosis of dura-attached supratentorial extra-axial ependymoma is difficult and often radiologically misdiagnosed as a meningioma. We report a case of dura-attached supratentorial extra-axial ependymoma that was misdiagnosed using intraoperative histological and cytological examinations.
A 26-year-old Japanese man with headache and nausea was referred to our medical facility. Magnetic resonance imaging revealed a cystic mass of 70 × 53 × 57 mm in the left temporoparietal lobe. A peritumoral band with hyperintensity on T2-weighted imaging was observed at the periphery of the lesion, suggesting an extra-axial lesion with no apparent connection to the ventricle. A dural tail sign was also noted on the gadolinium-enhanced T1-weighted image. Preoperative clinical diagnosis was meningioma. Proliferated tumor cells in sheets with intermingled branching vessels were observed in the frozen tissue. Perivascular rosettes were inconspicuous, and the tumor cells had rhabdoid cytoplasm. The tumor was intraoperatively diagnosed as a meningioma, suspected to be a rhabdoid meningioma. Perivascular rosettes were evident in the formalin-fixed paraffin-embedded tissues, suggesting ependymoma. The tumor cells had eosinophilic cytoplasm without a rhabdoid appearance. Anaplastic features, such as high tumor cellularity, increased mitotic activity, microvascular proliferation, and necrosis, were observed. Ependymal differentiation was confirmed on the basis of ultrastructural analysis. Molecular analysis detected C11orf95-RELA fusion gene. The final diagnosis was RELA fusion-positive ependymoma, World Health Organization grade III.
Owing to its unusual location, dura-attached supratentorial extra-axial ependymomas are frequently misdiagnosed as meningiomas. Neuropathologists should take great precaution in intraoperatively diagnosing this rare subtype of ependymoma to avoid misdiagnosis of the lesion as other common dura-attached tumors.
硬脑膜附着的幕上颅外脊索瘤是一种非常罕见的肿瘤，仅有 9 例报告。硬脑膜附着的幕上颅外脊索瘤的术前诊断较为困难，常常在影像学上误诊为脑膜瘤。我们报告了一例硬脑膜附着的幕上颅外脊索瘤，该肿瘤在术中组织学和细胞学检查中被误诊。
一名 26 岁的日本男性因头痛和恶心被转至我们的医疗机构。磁共振成像显示左颞顶叶有一个 70×53×57mm 的囊性肿块。病变外周观察到 T2 加权成像呈高信号的瘤周带，提示为无明显与脑室相连的颅外病变。钆增强 T1 加权图像上还观察到硬脑膜尾征。术前临床诊断为脑膜瘤。冷冻组织中观察到细胞呈片状增生，伴有分支血管。血管周围玫瑰花结不明显，肿瘤细胞具有横纹肌样细胞质。肿瘤在术中诊断为脑膜瘤，疑似横纹肌样脑膜瘤。在福尔马林固定石蜡包埋组织中观察到血管周围玫瑰花结，提示为脊索瘤。肿瘤细胞具有嗜酸性细胞质，无横纹肌样外观。观察到间变特征，如高肿瘤细胞密度、增加的有丝分裂活性、微血管增殖和坏死。基于超微结构分析确认存在室管膜分化。分子分析检测到 C11orf95-RELA 融合基因。最终诊断为 RELA 融合阳性的脊索瘤，世界卫生组织 3 级。
由于其位置不常见，硬脑膜附着的幕上颅外脊索瘤常误诊为脑膜瘤。神经病理学家在术中诊断这种罕见的室管膜瘤亚型时应格外小心，以避免将病变误诊为其他常见的硬脑膜附着肿瘤。
