第三腦室脊索樣膠質瘤影像學表現及鑒別診斷：附3例報道及文獻復習

汪文勝，方進，周全*，陳燕萍，成麗娜，吳靜，黃澤春

第三腦室脊索樣膠質瘤影像學表現及鑒別診斷：附3例報道及文獻復習

汪文勝1，方進2，周全2*，陳燕萍3，成麗娜1，吳靜1，黃澤春1

目的 探討CT及MRI對第三腦室脊索樣膠質瘤的診斷價值。材料與方法 收集經病理證實的3例第三腦室脊索樣膠質瘤患者，年齡 7～34歲，男2例，女1例；3例均行MRI檢查，其中2例行CT檢查；總結其臨床、影像學表現及病理資料，并復習相關文獻。結果 臨床表現主要為梗阻性腦積水、頭痛及神經內分泌紊亂癥狀。CT及MRI上腫瘤均位于第三腦室，并幕上腦室系統積水、擴張。CT多表現為體積較大的低密度腫塊，密度均勻，邊界清楚，未見囊變或壞死，鈣化少見(僅1例見病灶邊緣鈣化)。MRI上腫塊信號均勻，T1WI均呈低信號，T2WI均呈明顯高信號，增強掃描2例呈顯著不均勻強化，另1例呈顯著均勻強化。病理學表現為腫瘤細胞成簇或散在分布在黏液樣基質中，細胞疏密不等。瘤細胞核圓形、類圓形或偏位，染色質呈顆粒或凝塊狀，細胞核小、深染，核分裂少見，伴微囊形成，無壞死，可有小血管增生。免疫表型示所有瘤細胞均表達膠質纖維酸性蛋白(glial fibrillary acidic protein，GFAP)和波形蛋白(vimentin)。結論 第三腦室脊索樣膠質瘤影像表現具備一定特征性，結合臨床表現可作出診斷，最終確診需要根據病理及免疫組化檢查。

脊索樣膠質瘤；第三腦室；磁共振成像；體層攝影術，X線計算機

脊索樣膠質瘤(chordoid glioma)是一種罕見的第三腦室腫瘤，既往文獻主要探討腫瘤病理特點、免疫組化及起源問題，較少討論其影像學表現。本研究擬通過回顧性分析3例脊索樣膠質瘤的臨床、影像學表現及病理特征，探討CT及MRI在脊索樣膠質瘤診斷及鑒別診斷中的應用價值。

1 材料與方法

1.1 臨床資料及影像學表現

病例1：男，7歲。間斷性頭痛半年余，多食、多飲及多尿2個月。雙側眼底視乳頭水腫，邊界不清，色白，靜脈增粗，眼球活動良好。CT表現第三腦室低密度腫塊，CT值約20～28 Hu，腫塊周圍見高密度鈣化影；幕上腦室系統明顯擴張，腦室周圍見低密度水腫帶。MR示第三腦室腫塊T1WI呈低信號，T2WI呈明顯高信號，增強呈顯著不均勻強化，腫塊向下突入鞍上池，垂體柄及視交叉受壓，垂體未見明顯異常，腦室系統明顯積水擴張(圖1)。

病例2：男，25歲，左眼外側視野缺失1年，頭痛嘔吐5天。CT檢查發現第三腦室低密度腫塊，幕上腦室系統明顯擴張，腫塊邊界清楚；MRI表現為第三腦室異常信號腫塊影，T1WI呈低信號，T2WI呈明顯高信號，增強呈明顯均勻強化；腫塊向下突入鞍上池，向后突入腳間池，向右側侵犯右側丘腦，垂體柄及視交叉受壓，右側頸內動脈被腫塊包繞，幕上腦室系統明顯積水擴張(圖2)。

病例3：女，34歲，頭痛1月，加重伴嘔吐1天，近兩個月月經不規律。MRI示鞍上一腫塊影，腫塊T1WI呈低信號，T2WI呈明顯高信號，增強掃描呈不均勻強化，腫塊向下突入鞍上池，腦室系統明顯積水擴張。

2 病理檢查

2.1 鏡檢

光鏡下3例腫瘤有相似組織形態學表現，腫瘤細胞成簇或散在分布在黏液樣基質中，細胞疏密不等，細胞多呈梭形，有些見毛發狀突起，瘤細胞核圓形、類圓形或偏位，染色質呈顆粒或凝塊狀，細胞核小、深染，核分裂少見，伴微囊形成；腫瘤組織與周圍組織分界清楚；1例見鈣化。3例中均未見腫瘤性壞死，局部可見較多紅染的Rosenthal纖維，3例血管均明顯增生。

2.2 免疫組化

3例腫瘤瘤細胞胞質均表達GFAP(彌漫強+)、Vimentin(彌漫強+)，EMA(部分+)，3例均表達Syn，Ki-67均大于5%。Neu-N、TTF1(-)、CgA(-)、MGMT(-)、NSE(-)均陰性。

3 討論

脊索樣膠質瘤是一種罕見的腦腫瘤，多位于第三腦室前部，最早在1995年被認為是脊索樣腦膜瘤的一種變異類型[1]，隨著病理學免疫組化的發展，1998年Brat等[2]將其首先命名為脊索樣膠質瘤。2016年世界衛生組織(WHO)中樞神經系統腫瘤分類將其歸于“其他類型膠質瘤”，WHO II 級[3]。發病年齡12～70歲，平均年齡約為46歲，30～60歲多發，男：女約為1：2[4-7]，多見于成年女性，也可發生于兒童及嬰幼兒[8]，本研究3例中有1例為兒童。

脊索樣膠質瘤起源一直有爭議，Sato等[9]研究發現脊索樣膠質瘤的超微結構更接近于胚胎期的伸長細胞，伸長細胞可能位于第三腦室，由于脊索樣膠質瘤發生部位大多位于第三腦室前部，故普遍認為最可能起源于伸長細胞。也有研究認為病變起源于四疊體下丘、終板附近[10-12]，而Alfredo等[13]研究認為CD99陽性提示腫瘤起源于室管膜細胞分化。

第三腦室脊索樣膠質瘤臨床癥狀表現不一，主要由體積及具體位置決定，大多表現為梗阻性腦積水、頭痛；部分患者會有體重下降，神經內分泌紊亂征象(如甲狀腺功能低下、視力障礙、糖尿病性尿崩癥、閉經、月經失調等)，還有部分表現為神經精神癥狀(共濟失調、尿失禁、嗅覺減退)[7]。

圖1 男，7歲，MR軸位T2WI(A)見一類圓形均勻高信號腫塊，T1WI(B)病灶呈低信號，軸位T1WI增強掃描(C)病灶顯著不均勻強化，冠狀面T1WI增強掃描(D)顯示幕上腦室系統明顯擴張，右側額葉異常信號影為透明膈造瘺術+腦室腹腔分流術+第三腦室內病變活檢術后改變；HE染色(E)示背景稀疏，呈廣泛黏液樣變性，散布原漿型膠質細胞。細胞核小、深染，核分裂少見Fig. 1 A 7-year-old boy. MRI: Axial T2WI (A) showed an ovoid hyperintensity mass. The lesion showedhypointensity on T1WI (B) and heterogenously remarkable enhancement (C). Coronal images(D) showed theexpansion ofsupratentorial ventricles.The abnormal signal in the right frontallobe waspostoperative change. HE staining (E):Protoplasmic astrocyteswere scattered withinthewidespreadmyxoiddegeneration. Thenuclei were smallandhyperchromatic, nuclearfssion wererare.

圖2 男，25歲，CT (A)見第三腦室一低密度腫塊，腫瘤邊界清楚，體積較大。MRI：T2WI-Flair (B)呈均勻高信號，T1WI (C)呈均勻低信號，增強掃描腫塊呈明顯均勻強化(D)，矢狀位(E)示腫塊向下突入鞍上池，向后突入腳間池，幕上腦室系統明顯積水擴張，HE染色(F)示外周瘤組織與瘤組織周圍增生的的膠質細胞纖維束交織，免疫組化(G) GFAP染色陽性Fig. 2 A 25-year-old man, CT (A) showed a large, hypodensity mass in the third ventricle, with a clear boundary. MRI: The lesion showed homogeneous hypertensity on T2WI-Flair (B), hypointensity on T1WI (C) and homogeneously remarkable enhancement (D). The mass invaded into suprasellar cistern, backward into interpeduncular cistern, with the expansion of supratentorial ventricles (E). HE staining (F): tumor tissue is interweaved with glial cells fber. Immunohistochemistry staining (G): the staining for GFAP is positive.

脊索樣膠質瘤的組織病理學特征為腫瘤細胞成簇或散在分布在黏液樣基質中，細胞疏密不等，有些毛發狀突起，瘤細胞核圓形或類圓形或偏位，胞質豐富，染色質顆粒或凝塊狀，細胞核小、深染，無明顯核分裂像；腫瘤組織與周圍組織分界清楚；3例中均未見腫瘤性壞死，腫瘤周圍局部可見較多紅染的Rosenthal纖維，可伴有少許淋巴細胞、漿細胞浸潤，還可見Russel小體，3例血管明顯增生。該組病例中1例見鈣化，推測其由于腫瘤生長緩慢所致。免疫組化特點及鑒別診斷：3例腫瘤瘤細胞胞質均表達GFAP(彌漫強+)、Vimentin(彌漫強+)，EMA(部分+)，與既往文獻報道一致[14-17]。既往文獻Ki-67均＜5%，本組病例中3例均＞5%，可能由于本研究中腫瘤的增殖較活躍。

影像表現：第三腦室脊索樣膠質瘤診斷要點如下：(1)腫瘤多發生在第三腦室前部，體積較大，可呈浸潤性向周圍生長，多合并幕上腦室梗阻性腦積水；(2)腫瘤內部無明顯囊變、壞死及出血，鈣化少見，故CT上多密度較均勻，MR上多信號較均勻，CT上多呈較低密度，MR上T1WI呈低信號，T2WI呈明顯高信號，具備一定特征性；(3)增強后腫瘤顯著強化，可均一強化或不均一強化。另外，脊索樣膠質瘤的功能磁共振序列相關研究較少，既往有報道發現第三腦室脊索樣膠質瘤MRI灌注呈明顯低灌注，比腦膜瘤及惡性膠質瘤rCBV低[18]。

鑒別診斷[19-22]：若病灶有囊變或鈣化，應注意與顱咽管瘤鑒別；顱咽管瘤是鞍區最常見腫瘤，發病年齡呈10～20歲、50歲雙峰分布；可累及鞍上或鞍下，顱咽管瘤因多有囊變鈣化，T2WI信號多較混雜，實性部分呈明顯結節狀強化。另一鑒別診斷是垂體大腺瘤，可表現為蝶鞍擴大，向鞍上生長突破鞍膈呈典型“束腰征”，增強掃描病灶均勻強化，但T2WI以等信號為主，可以鑒別。兒童患者需與毛細胞型星形細胞瘤、生殖細胞瘤、室管膜瘤等鑒別。毛細胞型星形細胞瘤多見于兒童，可生長于鞍區，較大時可突入三腦室底部，典型多呈囊實性及壁結節樣強化、環形強化。異位的生殖細胞瘤常位于鞍區或鞍上，可壓迫三腦室，信號多呈稍長T1稍長T2信號，鈣化壞死少見，可見小范圍囊變，可沿腦脊液播散。松果體區若亦有病灶或者實驗室檢查若HCG(人絨毛膜促性腺激素)明顯升高均有助于生殖細胞瘤的診斷。室管膜瘤多位于側腦室、四腦室，三腦室室管膜瘤少見，少部分可位于腦內，發病年齡呈10～15歲及40～50歲雙高峰分布。腫塊多見分葉，與腦室壁呈廣基底相連，T1WI呈等或低信號，T2WI呈不均勻高信號，腫瘤內可見囊變、鈣化、出血，增強后呈中度不均勻強化。成年女性患者還應與腦膜瘤、中樞神經細胞瘤等鑒別，腦膜瘤好發于中年女性，腦室內好發于側腦室三角區，T1WI呈等或稍低信號，T2WI呈等或稍高信號，信號均勻，增強呈明顯均勻強化，囊變壞死少見。脈絡叢乳頭狀瘤好發于5歲以下兒童，也好發于側腦室三角區，常累及室管膜下腦白質，表面多呈顆粒狀，T1WI呈等或低信號，T2WI呈等或少高信號，信號不均勻，增強后顯著強化，多伴有交通性腦積水。中樞神經細胞瘤多見于中青年人，透明隔、室間孔區多見，信號不均勻，可見流空血管影，囊變鈣化較多見，增強掃描實性部分呈中等或明顯不均勻強化。

綜上所述，第三腦室脊索樣膠質瘤影像學表現具備一定特征性，結合臨床表現可以作出診斷，最終確診需要根據病理及免疫組化檢查。

[References]

[1] Wanschitz J, Schmidbauer M, Maier H, et al. Suprasellar meningioma with expression of glial fbrillary acidic protein: a peculiar variant. Acta Neuropathol, 1995, 90(5): 539-544.

[2] Brat DJ, Scheithauer BW, Staugaitis SM, et al. Third ventricular chordoid glioma: a distinct clinicopathologic entity. J Neuropathol Exp Neurol, 1998, 57(3): 283-290.

[3] Louis DN, Perry A, Reifenberger G, et al. The 2016 World Health Organization classifcation of tumors of the central nervous system: a summary. Acta Neuropathol, 2016, 131(6): 803-820.

[4] Castellano-Sanchez AA, Schemankewitz E, Mazewski C, et al. Pediatric chordoid glioma with chondroid metaplasia. Pediatr Dev Pathol, 2001, 4(6): 564-567.

[5] Goyal R, Vashishta RK, Singhi S, et al. Extraventricular unusual glioma in a child with extensive myxoid change resembling chordoid glioma. J Clin Pathol, 2007, 60(11): 1294-1295.

[6] Jain D, Sharma MC, Sarkar C, et al. Chordoid glioma: report of two rare examples with unusual features. Acta Neurochir (Wien), 2008, 150(3): 295-300.

[7] Bongetta D, Risso A, Morbini P, et al. Chordoid glioma: a rare radiologically, histologically, and clinically mystifying lesion. World Journal of Surgical Oncology, 2015, 13(1): 188.

[8] Buccoliero AM, Caldarella A, Gallina P, et al. Chordoid glioma:clinicopathologic profle and differential diagnosis of an uncommon tumor. Arch Pathol Lab Med, 2004, 128(11): 141-145.

[9] Sato K, Kubota T, Ishida M, et al. Immunohisochemical and ultrastructural study of chordoid glioma of the third ventricle: its anycytic differentiation. Acta Neuropathol, 2003, 106(2): 176-180.

[10] Leeds NE, Lang FF, Ribalta T, et al. Origin of chordoid glioma of the third ventricle. Arch Pathol Lab Med, 2006, 130(4): 460-464.

[11] Suh YL, Kim NR, Kim JH, et al. Suprasellar chordoid glioma combined with Rathke's cleft cyst. Pathol Int, 2003, 53(11): 780-785.

[12] Wang WS. One case report: Chordoid glioma of the third ventricle. Zhonghua Fang She Xue Za Zhi, 2007, 41(8): 892-893.

汪文勝. 第三腦室脊索瘤樣膠質瘤一例. 中華放射學雜志, 2007, 41(8): 892-893.

[13] Romero-Rojas AE, Díaz-Pérez JA, Ariza-Serrano LM. CD99 is expressed in chordoid glioma and suggests ependymal origin. Virchows Arch, 2012, 460(1): 119-122.

[14] Ni HC, Piao YS, Lu DH, et al. Chordoid glioma of the third ventricle: four cases including one case with papillary features. Neuropathology, 2013, 33(2): 134-139.

[15] Takei H, Bhattacharjee MB, Adesina AM. Chordoid glioma of the third ventricle: report of a case with cytologic features and utility during intraoperative consultation. Acta Cytol, 2006, 50(6): 691-696.

[16] Kobayashi T, Tsugawa T, Hashizume C, et al. Therapeutic approach to chordoid glioma of the third ventricle. Neurol Med Chir (Tokyo), 2013, 53(4): 249-255.

[17] Zhao FX, Wang CN, Shi QL, et al. Chordoid glioma of the third ventricle: a report of three cases and review of literature. J Clin Exp Pathol, 2008, 24(4): 399-406.

趙飛行, 汪春年, 石群立, 等. 第三腦室脊索樣膠質瘤3例報道及文獻復習. 臨床與實驗病理學雜志, 2008, 24(4): 399-406.

[18] Grand S, Pasquier B, Gay E, et al. Chordoid glioma of the third ventricle: CT and MRI, including perfusion data. Neuroradiology, 2002, 44(10): 842-846.

[19] Restrepo R, Howard LH, Robinson MJ. Chordoid glioma: A novel tumor of the third ventricle. Ann Diagn Pathol, 2000, 4(6): 373-378.

[20] Cheng WY, Luo L, Ma J. Chordoid meningioma in third ventricle: one case report. Chin J Magn Reson Imaging, 2011, 2(1): 75-76.

程婉瀅, 羅麟, 馬軍. 第三腦室脊索樣腦膜瘤1例. 磁共振成像, 2011, 2(1): 75-76.

[21] Song Q, Qi YT, Li Y. Chordoid glioma of the third ventricle: one case report. Chin J Magn Reson Imaging, 2011, 2(2): 157-158.

宋茜, 齊悅彤, 李瑩. 第三腦室脊索樣膠質瘤1例. 磁共振成像, 2011, 2(2): 157-158.

[22] Shi HY, Tian Y, Shi YZ, et al. The MRI fndings in chordoid glioma of the third ventricle. Natl Med J China, 2013, 93(5): 373-375.

史紅媛, 田迎, 史玉振, 等. 第三腦室脊索樣膠質瘤的MRI表現. 中華醫學雜志, 2013, 93(5): 373-375.

(5)關心、支持本刊工作，維護本刊榮譽，積極宣傳和推廣本刊，并且積極參加本刊組織的各項學術活動。(6)原則上具有副高以上職稱，碩士研究生以上學歷。特別優秀的可以破格錄用：以第一作者在美國SCI收錄期刊發表過論文的碩士研究生以上學歷的人員可以不受職稱限制；在國內首發過MR領域新研究方法、新臨床應用論文的人員可以不受職稱、學歷限制；在國外進修1年以上人員不受職稱限制；國家級基金課題第一負責人不受職稱限制。(7)歡迎海外華人學者審稿。海外學者需支持中國統一大業，能看中文文獻，有2位以上本刊編委推薦，推薦表可不蓋單位公章。(8)本人自愿申請、親筆簽名，愿意承擔本刊審稿專家義務。所在科室/部門主任同意，推薦表蓋所在單位公章。

審稿專家推薦表請在官網www.cjmri.cn下載中心下載。

Chordoid glioma in the third ventricle: image fndings and differential diagnosis: a report of three cases and review of the literature

WANG Wen-sheng1, FANG Jin2, ZHOU Quan2*, CHEN Yan-ping3, CHENG Li-na1, WU Jing1, HUANG Ze-chun11Department of Imaging Center, Guangdong 999 Brain Hospital, Guangzhou 510510, China
2Medical Imaging Center, the First Affliated Hospital of Jinan University, Guangzhou 510630, China
3Medical Imaging Center, Nanfang Hospital Affiliated Southern Medical University, GuangZhou 510515, China

Objective: To summarize the CT and MRI findings and differential diagnosis of chordoid glioma in the third ventricle and to explore the diagnostic value of imaging examination. Materials and Methods: Three patients (two males and one females; range, 7-34 years) with chordoid glioma in the third ventricle confrmed by biopsy pathology were enrolled. The symptoms, imaging findings and pathology were retrospectively analyzed, and then a review of the literature was performed. Results: The symptoms were usually obstructive hydrocephalus, progressive headache, neuroendocrine symptoms. All the three tumors located in the third ventricle. The tumor usually represented as a large, well-circumscribed ovoid and hypodense lesion on CT. No cystic or necrotic changes were found. Only one case had peripheral calcification, as hyperdense on CT. On MRI, the lesions all showed homogeneous hypointensity on T1-weighted image and hyperintensity on T2-weighted image. Two cases showed heterogenously enhancement, while the other one showed homogeneously enhancement. Microscopically, the tumor cells arranged in clusters or scattered in a mucinous background. Tumor cell nucleus were round, oval or offset, chromatin were granulated or nubby, the nuclei were small and hyperchromatic, nuclear fission were rare. Necrosis was not identified, new blood vessels showed proliferation. Immunohistochemically, tumor cellswere stained positively for GFAP and vimentin. Conclusion: There are several characteristic CT and MRI findings of chordoid glioma in the third ventricle. The diagnosis can be made when combining image fndings with clinical fndings. The fnal diagnosis should be confrmed by histopathology and immunohistochemical staining．

Chordoid glioma; Third ventricle; Magnetic resonance imaging; Tomography, X-ray computed

1.廣東三九腦科醫院影像中心，廣州510510

2.暨南大學附屬第一醫院醫學影像中心，廣州 510630

3.南方醫科大學附屬南方醫院醫學影像中心，廣州 510515

周全，E-mail：tzq@jnu.edu.cn

2016-06-17

接受日期：2016-09-06

R445.2；R739.41

A

10.12015/issn.1674-8034.2016.10.006汪文勝, 方進, 周全, 等. 第三腦室脊索樣膠質瘤影像學表現及鑒別診斷：附3例報道及文獻復習. 磁共振成像, 2016, 7(10): 749-753.

*Correspondence to: Zhou Q, E-mail: tzq@jnu.edu.cn

Received 17 Jun 2016, Accepted 6 Sep 2016