陈绪珠

CHEN Xu-zhu

首都医科大学附属北京天坛医院神经影像中心， 北京 100050

Imaging center of neuroradiology, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China

患者，女，14岁。因“阵发性头痛3月，加重2月”入院。既往体健，无恶心、呕吐、眩晕、复视及抽搐等，体检病理征阴性。

影像学检查：CT扫描示后颅窝及鞍旁巨大低密度病变，最大径约5.7 cm，CT值4HU左右，病变无钙化，分叶状，边界清晰，斜坡左上部分不规则骨质破坏(图1A，B)。MRI检查，病变呈长T1、长T2信号改变，信号较均匀，弥散加权成像(diffusion weighted imaging, DWI)在b=1000 s/mm2时病变弥散受限，呈高信号改变，增强扫描，病变边缘和内部均未见强化(图2A-D)。术前诊断为后颅窝胆脂瘤。

图1 轴位CT平扫示斜坡周围分叶状病变，呈均匀性低密度改变(A)，冠状位多平面重建(MPR)显示左侧斜坡骨质破坏(B)图2 头部MRI平扫、DWI扫描及增强扫描。轴位平扫示病变呈长T1(2A)、长T2信号改变(2B)，信号较均匀，于DWI上(b=1000 s/mm2)呈高信号改变(2C)。矢状位增强扫描，病变无强化(2D)，可见斜坡破坏(黑箭)和强化的血管(白箭)Fig 1 Axial CT scan showing a lobular lesion located in the clival region.It is homogenously low attenuation (A), and coronal multiplar reconstruction (MPR) demonstrating the destruction of the left clivus (B).Fig 2 Head MRI scan.Pre-contrast axial revealing the lesion of homogenous low signal on T1WI (2A) and high signal on T2WI(2B).It is high signal on DWI (2C).Post-contrast sagittal MRI indicating non-enhancement of the tumor.Note the destruction of the clivus (black arrow) and enhanced normal vessel (white arrow).

图3 病理学检查。光镜下，在粘液样和无结构的基质中有不规则的透明细胞散在或成群分布，细胞形状不一(H and E ×200,3A)。免疫组化显示S-100阳性(3B)，细胞角蛋白阳性(3C)Fig 3 Pathological examination.Light microscope shows that, in the myxoid and non-structural substrate, there are irregular clear cells, which are scattered or clustered in distribution and variable in shape (H and E ×200, 3A).Immunohistochemistry stain indicating positive reaction for S - 100 (×100, 3B) and positive reaction for cell keratin (×100, 3C).

术中所见：肿瘤位于斜坡周围，破坏斜坡及硬膜，侵入蝶窦，大小约5.7 cm×5.5 cm×4.5 cm。质地较软，灰色，血供较差。显微镜下全切肿瘤。病理学诊断为脊索瘤(图3A-C)。术后患者恢复良好，于术后第7天出院。

讨论

脊索瘤占颅内所有肿瘤的0.1%～0.2%，骨质破坏是典型表现之一[1]。病变内常见坏死、囊变及钙化，故多表现为CT图像上密度不均匀，MRI图像上信号混杂。增强扫描，病变常中度到明显强化[2]。

脊索瘤明显囊变的机制尚未明了。……