第326课（中枢神经）病例探析（088）—室管膜下瘤

第326课（中枢神经）病例探析（088）—室管膜下瘤女，46岁，1年前无明显诱因出现眩晕，每次持续几分钟，发作时不能走路，并伴恶心室管膜下瘤( subependymoma,SE)是一种罕见、生长缓慢的良性肿瘤, Schenker于 1945 年首次命名,属于室管膜来源肿瘤,WHOI 级。

2016年 WHO新分类中室管膜肿瘤( ependymal tumors)的其他肿瘤包括黏液乳头型室管膜瘤、室管膜瘤、RELA 融合阳性室管膜瘤与间变性室管膜瘤,后者为WHOⅢ级。

SE约占室管膜肿瘤的8%。

SE起源于多潜能的室管膜-星形细胞的前体细胞。

病理学上肿瘤含有室管膜细胞和星形细胞,其中星形细胞占50%。

镜下为簇状细胞核埋入致密的胶质细胞纤维基质中,常伴小囊腔形成,核分裂偶见或无。

瘤细胞核形态一致,类似于管膜下胶质细胞,偶见多形核。

易见小而融合的囊腔及钙化与出血。

肿瘤微血管可增生,偶见细胞突起围绕于血管周围,形成假菊形团,此时可诊断为混合性室管膜瘤/室管膜下瘤。

本病可见于各年龄段,但好发于中老年,85%以上超过15岁,男性较多。

临床表现与肿瘤所在部位有关,常出现脑积水。

Subependymoma (SE) is a rare, slow-growing benign tumor, Schenker was first named in 1945, belongs to ependymal source tumor,WHOI grade. In 2016 the WHO classification of ependymal tumor (ependymal tumors) of other tumors including mucous nipple ependymoma, ependymoma, a positive RELA fusion ependymoma and anaplastic ependymoma, which is a category WHO Ⅲ. SE accounted for about 8% of ependymal tumors. SE originates from the pluripotent ependymal precursor of astrocytes. Pathologically, the tumor contains ependymal cells and astrocytes, 50% of which are astrocytes. Microscopically, the nuclei are clustered into a dense glial fibrous matrix, often accompanied by the formation of small cysts, with or without nuclear division. The tumor nuclei are uniform, similar to subtubular glial cells, with occasional polymorphisms. Small fused lumens, calcification, and hemorrhage are common. Tumor microvessels may proliferate, with occasional cellular protuberances surrounding blood vessels to form pseudochrysanthemum masses. At this point, mixed ependymoma/subependymoma can be diagnosed. The disease can be seen in all age groups, but often occurs in the elderly, more than 85% over 15 years old, more male. Clinical manifestations are associated with the location of the tumor, often hydrocephalus.CT病灶形态可为类圆形、圆形、结节状或不规则形,边界清。

室管膜下瘤CT平扫病灶多呈均匀等密度肿块,部分可见钙化,部分肿瘤内可有囊变。

室管膜下瘤血供较差,血脑屏障相对完整,含有丰富的胶质纤维,肿瘤一般不强化或仅有轻微强化。

发生于侧脑室者,常致侧脑室扩大,并可经室间孔侵入第三脑室,阻塞双侧室间孔,导致双侧侧脑室扩大。

第四脑室室管膜下瘤常阻塞中脑导水管致幕上脑室系统扩大CT lesions can be round, round, nodular or irregular, with clear boundary. Subependymal neoplasms on CT scan were mostly uniformly dense masses with calcification and cysts in some tumors. The blood supply of subependymal tumors is poor, the blood-brain barrier is relatively complete, and the tumors are rich in glial fibers. In the case of lateral ventricles, the lateral ventricles are usually enlarged, and the third ventricle can be invaded through the interventricular foramen to block the bilateral interventricular foramen, resulting in the enlargement of bilateral lateral ventricles. Subependymal tumors of the fourth ventricle often block the midbrain aqueduct and expand the supratentorial ventricular systemMR室管膜下瘤呈类圆形、椭圆形或分叶状,边界清楚。

肿瘤实性部分在T1WI上多表现为较均匀的等信号或略低信号,肿瘤内可无囊变或伴数量不等的小囊状低信号区,个别病例也可有较大的囊状低信号区,囊状低信号区为富含黏液的囊状结构。

T2WI肿瘤呈较均匀的高信号,T2- FLAIR呈高信号,囊变区呈水样极高信号。

由于室管膜下瘤瘤体中实性部分和囊性部分比例不同,其MR表现也不完全一致,当肿瘤内局灶性囊变较多,或伴有钙化、含铁血黄素沉积以及硬化的肿瘤血管时,MRI信号可不均匀。

T1WI增强扫描,室管膜下瘤大多数无明显强化或轻度强化,少数有不典型的中度强化,偶尔可见强化的肿瘤血管蒂。

MRS符合良性肿瘤波谱特征,表现为NAA峰轻度降低,Cho峰正常。

MR subependymal tumors were round, oval or lobulated, with clear boundaries. The solid part of the tumor mostly showed uniform isosignal or slightly low signal on T1WI, and there was no cystosis or small cystlike low signal area with different number of patients. Some cases also had large cystlike low signal area,which was a mucus-rich cystic structure. T2WI tumor showed relatively uniform hypersignal, t2-flair showed hypersignal, and the cystic area showed extremely high water signal. As the proportion of solid and cystic parts of the subependymal tumor is different, the MR manifestations are not completely consistent. When there are more focal cystic changes in the tumor, or calcification, hemosiderosis and sclerotic tumor vessels,MRI signals are not uniform. On T1WI enhanced scan, most subependymal tumors had no obvious enhancement or mild enhancement, a few had atypical moderate enhancement, and occasionally had an enhanced tumor vascular pedicle. MRS was consistent with the spectrum characteristics of benign tumor, showing a slight decrease in NAA peak and a normal Cho peak.室管膜下瘤好发于成年男性,多位于第四脑室和侧脑室,一般为团块状,边缘较清楚,以下几点对室管膜下瘤的诊断具有一定的参考意义:①符合一般良性肿瘤的特征,表现为侧脑室内膨胀性生长,边界多较清晰,常黏附于侧脑室壁或透明隔而不侵犯邻近脑组织,瘤周脑组织一般无水肿;②CT平扫肿瘤呈低或等密度,部分有点状、沙砾样钙化,第四脑室室管膜下瘤钙化出现率近50%;③多发小囊变在室管膜下瘤诊断中具有一定的特征性, 小囊变区呈散在分布,有时可融合成囊腔,囊变区为富含黏液的囊状结构;④增强扫描肿瘤无或轻度局灶性强化,可能与肿瘤富含胶质纤维并伴有多发小囊状结构有关,是此肿瘤的另一重要特征;⑤由于肿瘤细胞呈散在或簇状分布,致水分子扩散运动不受限,故DWI呈等或低信号;⑥肿瘤内出血少见;⑦肿瘤位于室间孔处或肿瘤较大时引起室间孔狭窄或闭塞时可导致脑积水;⑧MRS上,NAA峰来源于室管膜细胞和胶质上皮细胞的中枢神经上值稍降低,Cho峰值正常,符合良性肿瘤的特征,室管膜下瘤MRS显示的正常Cho峰对诊断该肿瘤有一定的参考意义。