第三腦室脊索樣膠質(zhì)瘤影像學表現(xiàn)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(zhì)瘤影像學表現(xiàn)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(zhì)瘤的診斷價值。材料與方法 收集經(jīng)病理證實的3例第三腦室脊索樣膠質(zhì)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(jié)其臨床、影像學表現(xiàn)及病理資料，并復習相關文獻。結(jié)果 臨床表現(xiàn)主要為梗阻性腦積水、頭痛及神經(jīng)內(nèi)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(tǒng)積水、擴張。CT多表現(xiàn)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(xiàn)為腫瘤細胞成簇或散在分布在黏液樣基質(zhì)中，細胞疏密不等。瘤細胞核圓形、類圓形或偏位，染色質(zhì)呈顆?；蚰龎K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(zhì)纖維酸性蛋白(glial fibrillary acidic protein，GFAP)和波形蛋白(vimentin)。結(jié)論 第三腦室脊索樣膠質(zhì)瘤影像表現(xiàn)具備一定特征性，結(jié)合臨床表現(xiàn)可作出診斷，最終確診需要根據(jù)病理及免疫組化檢查。

脊索樣膠質(zhì)瘤；第三腦室；磁共振成像；體層攝影術(shù)，X線計算機

脊索樣膠質(zhì)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(xiàn)。本研究擬通過回顧性分析3例脊索樣膠質(zhì)瘤的臨床、影像學表現(xiàn)及病理特征，探討CT及MRI在脊索樣膠質(zhì)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(xiàn)

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(cè)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(xiàn)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(tǒng)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(tǒng)明顯積水擴張(圖1)。

病例2：男，25歲，左眼外側(cè)視野缺失1年，頭痛嘔吐5天。CT檢查發(fā)現(xiàn)第三腦室低密度腫塊，幕上腦室系統(tǒng)明顯擴張，腫塊邊界清楚；MRI表現(xiàn)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(cè)侵犯右側(cè)丘腦，垂體柄及視交叉受壓，右側(cè)頸內(nèi)動脈被腫塊包繞，幕上腦室系統(tǒng)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(jīng)不規(guī)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(tǒng)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(tài)學表現(xiàn)，腫瘤細胞成簇或散在分布在黏液樣基質(zhì)中，細胞疏密不等，細胞多呈梭形，有些見毛發(fā)狀突起，瘤細胞核圓形、類圓形或偏位，染色質(zhì)呈顆?；蚰龎K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(zhì)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(zhì)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(fā)展，1998年Brat等[2]將其首先命名為脊索樣膠質(zhì)瘤。2016年世界衛(wèi)生組織(WHO)中樞神經(jīng)系統(tǒng)腫瘤分類將其歸于“其他類型膠質(zhì)瘤”，WHO II 級[3]。發(fā)病年齡12～70歲，平均年齡約為46歲，30～60歲多發(fā)，男：女約為1：2[4-7]，多見于成年女性，也可發(fā)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(zhì)瘤起源一直有爭議，Sato等[9]研究發(fā)現(xiàn)脊索樣膠質(zhì)瘤的超微結(jié)構(gòu)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(zhì)瘤發(fā)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(zhì)瘤臨床癥狀表現(xiàn)不一，主要由體積及具體位置決定，大多表現(xiàn)為梗阻性腦積水、頭痛；部分患者會有體重下降，神經(jīng)內(nèi)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(jīng)、月經(jīng)失調(diào)等)，還有部分表現(xiàn)為神經(jīng)精神癥狀(共濟失調(diào)、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(tǒng)明顯擴張，右側(cè)額葉異常信號影為透明膈造瘺術(shù)+腦室腹腔分流術(shù)+第三腦室內(nèi)病變活檢術(shù)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(zhì)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(tǒng)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(zhì)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(zhì)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(zhì)中，細胞疏密不等，有些毛發(fā)狀突起，瘤細胞核圓形或類圓形或偏位，胞質(zhì)豐富，染色質(zhì)顆?；蚰龎K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(zhì)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(xiàn)：第三腦室脊索樣膠質(zhì)瘤診斷要點如下：(1)腫瘤多發(fā)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(nèi)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(zhì)瘤的功能磁共振序列相關研究較少，既往有報道發(fā)現(xiàn)第三腦室脊索樣膠質(zhì)瘤MRI灌注呈明顯低灌注，比腦膜瘤及惡性膠質(zhì)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(qū)最常見腫瘤，發(fā)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(jié)節(jié)狀強化。另一鑒別診斷是垂體大腺瘤，可表現(xiàn)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(qū)，較大時可突入三腦室底部，典型多呈囊實性及壁結(jié)節(jié)樣強化、環(huán)形強化。異位的生殖細胞瘤常位于鞍區(qū)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(qū)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(cè)腦室、四腦室，三腦室室管膜瘤少見，少部分可位于腦內(nèi)，發(fā)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(nèi)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(jīng)細胞瘤等鑒別，腦膜瘤好發(fā)于中年女性，腦室內(nèi)好發(fā)于側(cè)腦室三角區(qū)，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(fā)于5歲以下兒童，也好發(fā)于側(cè)腦室三角區(qū)，常累及室管膜下腦白質(zhì)，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(jīng)細胞瘤多見于中青年人，透明隔、室間孔區(qū)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(zhì)瘤影像學表現(xiàn)具備一定特征性，結(jié)合臨床表現(xiàn)可以作出診斷，最終確診需要根據(jù)病理及免疫組化檢查。

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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(yī)院影像中心，廣州510510

2.暨南大學附屬第一醫(yī)院醫(yī)學影像中心，廣州 510630

3.南方醫(yī)科大學附屬南方醫(yī)院醫(yī)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(zhì)瘤影像學表現(xiàn)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