髓母肌母细胞瘤：一例成人病例报告及文献复习

目的报告1例临床少见的髓母肌母细胞瘤病例,探讨其临床病理学特征。方法对1例成人小脑髓母肌母细胞瘤患者的临床表现、组织形态学及免疫组织化学特征进行回顾分析,并复习相关文献。结果临床主要表现为持续性头痛,呈阵发性加重。MRI检查显示,病变位于右侧小脑半球及蚓部,呈混杂信号影,病灶边界欠清晰,有水肿改变,第四脑室明显受压,合并幕上脑室扩张、积水。手术切除肿瘤,组织形态学观察显示肿瘤细胞紧密排列,呈弥漫片状,密度较高,可见两种细胞成分,一种为卵圆形或短梭形小细胞,异型性明显,细胞核深染,几无细胞质;另一种为胞体较大的圆形或卵圆形肿瘤细胞,异型性明显,细胞核部分呈空泡状,有丰富的嗜伊红颗粒状细胞质。免疫组织化学染色显示,肿瘤细胞突触素、胶质纤维酸性蛋白、结蛋白、肌调节蛋白1、波形蛋白及神经元核抗原表达阳性,神经微丝和上皮膜抗原呈局灶性表达,而平滑肌肌动蛋白和白细胞共同抗原表达阴性;其中结蛋白和肌调节蛋白1表达阳性的肿瘤细胞,经证实为横纹肌分化。结论髓母肌母细胞瘤为髓母细胞瘤中极为少见的临床亚型,主要由髓母细胞瘤和横纹肌成分共同组成,好发于儿童,成人偶有发生,患者预后差。     

第三脑室脂肪神经细胞瘤

目的探讨中枢神经系统小脑外脂肪神经细胞瘤的临床病理特征、诊断与鉴别诊断要点,以及影响预后的因素。方法与结果女性患者,52岁。临床仅表现为头痛,CT显示中线前区域低密度病灶。术中可见肿瘤位于第三脑室前,大小约5.80 cm×4.00 cm×3.80 cm。组织学特征呈明显双相性,由大小一致的小圆形细胞和成熟脂肪细胞及其脂肪样细胞构成,有成熟骨组织、部分区域密集钙化灶形成,无坏死和核分裂象;肿瘤细胞弥漫表达S-100蛋白、β-连接素,少数表达神经元核抗原、突触素、鼠双微体2、P53,不表达胶质纤维酸性蛋白、少突胶质细胞转录因子-2、异柠檬酸脱氢酶1、结蛋白、CD68、髓鞘碱性蛋白,Ki-67抗原标记指数约为1%。结论中枢神经系统脂肪神经细胞瘤临床罕见,主要发生于小脑,小脑以外脑组织极为罕见,明确诊断依赖其独特的组织形态学特征和免疫组织化学表型。患者预后良好,生存期超过5年,最长可超过18年。     

少见的脊髓脑室外神经细胞瘤临床病理分析

研究背景 脑室外神经细胞瘤是新近分类的肿瘤实体,可发生于中枢神经系统除脑室外的任何部位,但发生于脊髓者极为少见.由于缺乏特征性影像学表现,术前难以明确诊断;又因其组织形态学和免疫组织化学表型的相似性,易误诊为好发于脊髓的其他肿瘤.鉴于此,本文着重探讨原发于脊髓的脑室外神经细胞瘤的临床病理学特征,并通过对以往文献的复习,分析其诊断要点,以期提高临床对脑室外神经细胞瘤的鉴别诊断能力.方法与结果 男性患者,47岁.因近1年进行性双上肢无力和颈部疼痛入院.颈部MRI显示脊髓C6～T3节段髓内占位性病变,T1WI呈等或低信号、T2WI呈高信号,增强后病灶呈不均匀强化.术中可见肿瘤位于脊髓内,无包膜,与周围组织分界清楚,血运丰富,与硬脊膜无粘连.肿瘤组织由弥漫片状或团簇状分布的肿瘤细胞构成,部分区域肿瘤细胞呈圆形,大小形态较一致,有核周空晕,呈少突胶质细胞瘤样特点;部分区域肿瘤细胞排列较致密,呈短梭形,无核周空晕,呈放射状排列或围绕在血管周围形成不典型“菊形团”结构,类似室管膜瘤样结构.肿瘤组织中未见无核神经纤维岛和神经节样细胞,以及核分裂象和出血坏死.免疫组织化学染色显示两种形态肿瘤细胞弥漫性强阳性表达突触素,灶性表达神经元特异性烯醇化酶、S-100蛋白和少突胶质细胞转录因子-2,但不表达波形蛋白、细胞角蛋白、上皮膜原、神经元核抗原和胶质纤维酸性蛋白,Ki-67抗原标记指数＜1％.病理诊断为脊髓脑室外神经细胞瘤.结论 脊髓脑室外神经细胞瘤临床罕见,可能起源于胚胎时期脊髓中央管周围的神经元前体细胞,须经组织学观察明确诊断.尽管大多数脑室外神经细胞瘤患者肿瘤全切除后预后良好,但出现不典型组织学表现者建议术后辅助放射治疗以减少复发.应注意与具有透明细胞特征、室管膜瘤样特征及其他具有相似组织学结构的脊髓肿瘤相鉴别.     

鞍区和鞍上脑室外神经细胞瘤

目的探讨发生于鞍区和鞍上的脑室外神经细胞瘤的临床病理学特征。方法对1例鞍区和鞍上脑室外神经细胞瘤患者的临床表现、影像学特征、组织学形态、免疫表型和分子遗传学特征进行回顾分析并复习相关文献。结果女性患者,27岁,临床表现为反复头痛伴双眼视物模糊5个月。头部MRI显示鞍区和鞍上占位性病变,T_1WI呈等或低信号,T_2WI呈高或低混杂信号,扩散加权成像呈稍高信号,界限清晰,正常垂体结构显示不清。临床诊断为垂体腺瘤,行经鼻蝶入路垂体腺瘤切除术+脑脊液鼻漏修补术+视神经减压术,手术全切除肿瘤。组织学形态可见肿瘤细胞呈弥漫浸润性生长,部分区域可见神经毡背景;肿瘤细胞大小和形态相对一致,胞核圆形或卵圆形,染色质细腻深染,未见核分裂象。免疫组织化学染色可见肿瘤细胞胞核表达神经元核抗原和甲状腺转录因子-1,胞核和胞质表达钙视网膜蛋白,胞质表达突触素、嗜铬素A、上皮钙黏素和基质金属蛋白酶-9;胞核局灶性表达S-100蛋白,胞质局灶性表达神经微丝蛋白、细胞角蛋白8和波形蛋白;Ki-67抗原标记指数约为3%。网织纤维染色呈阴性。基因检测可见肿瘤细胞无异柠檬酸脱氢酶基因突变,无1p/19q-共缺失。最终病理诊断为脑室外神经细胞瘤(WHOⅡ级)。结论鞍区和鞍上脑室外神经细胞瘤临床极为罕见,组织学形态与发生于脑室的中枢神经细胞瘤相似,表现为肿瘤弥漫浸润性生长,肿瘤细胞形态较一致,胞核圆形,可见神经毡背景和"树枝"状薄壁毛细血管。应注意与垂体腺瘤、少突胶质细胞瘤和透明细胞型室管膜瘤等相鉴别。     

原发性中枢神经系统淋巴瘤影像学及病理学特征临床研究

目的探讨原发性中枢神经系统淋巴瘤的临床表现、影像学和病理学特征。方法回顾分析6例经术后病理学检查证实的原发性中枢神经系统淋巴瘤患者的临床资料,分析其临床表现、影像学和组织病理学特征。结果原发性中枢神经系统淋巴瘤临床表现多样,以头痛、头晕多见。6例患者中肿瘤单发5例、多发1例,共7个病灶,病灶位于大脑半球4个、小脑1个、侧脑室1个、丘脑1个,其中2个病灶累及胼胝体。病灶多呈类圆形或不规则形,边界较清晰,肿瘤周围水肿和占位效应相对较轻。CT显示肿瘤呈高密度,T1WI呈等或略低信号、T2WI呈等或稍高信号、增强扫描肿瘤呈均匀强化。所有患者均行手术治疗。光学显微镜观察,肿瘤细胞围绕血管周围分布,形成"袖套"样浸润;免疫组织化学表型分析,肿瘤均来源于B淋巴细胞。结论原发性中枢神经系统淋巴瘤影像学和病理学表现具有一定特异性,主要病理学类型为弥漫性大B细胞淋巴瘤,组织学形态和免疫组织化学表型分析是明确诊断的"金标准"。     

原发性中枢神经系统淋巴瘤非典型MRI影像学表现

目的总结原发性中枢神经系统淋巴瘤(PCNSL)非典型MRI影像学表现,以提高对非典型PCNSL影像诊断的正确率。方法回顾性分析经穿刺或手术病理证实的25例原发性中枢神经系统淋巴瘤的MRI影像学表现,包括非典型的生长部位,非特异的MRI表现和强化方式。结果 25例中单发病灶者16例,多发病灶9例,病灶数共38个。不典型发生部位可见于鞍上、脑干、小脑半球和小脑蚓部、侧脑室、三脑室和第四脑室等等。病灶形态大小不一,表现形式多种多样,可呈类圆形、不规则形,团块状、结节状、斑片状、灶状或散在分布。1例病灶侵及邻近脑膜,出现"脑膜尾征"。20例在T1WI呈稍低或等信号,T2WI呈等或稍高信号,5例T1WI、T2WI呈混杂信号。7例呈实性均质强化,6例呈结节状强化,3例呈斑片状强化,2例呈条纹状强化,2例呈环形强化,1例呈弥漫肿胀伴轻度强化,3例多发病灶多种强化方式并存。5例DWI呈均质高信号,6例呈不均匀稍高信号,4例呈中等信号。MRS检查4例出现较明显的Lip峰。结论对于发生在非典型生长部位、影像学表现非特异性的,以及颅内多发病灶的和侵犯脑膜的中枢神经系统淋巴瘤,术前诊断较为困难,需引起高度重视。     

松果体母细胞瘤一例报告并文献复习

目的 探讨松果体母细胞瘤患者的临床和病理学特征,并复习相关文献.方法 与结果一例12 岁女性患者,无明显诱因头痛3年.头部MRI检查显示松果体区椭圆形等T1、等或低T2信号影,大小约2.70cm×2.00cm,增强扫描呈明显均匀强化.手术中可见肿瘤组织呈暗红色,边界尚清楚,有出血灶,分块切除肿瘤组织和包膜后第三脑室和侧脑室脑脊液通畅流出.光学显微镜观察肿瘤细胞呈弥散或片状密集排列,组织发生大片凝固性坏死;肿瘤细胞形态较小,细胞核呈圆形或不规则形,核深染、异型性明显、分裂象多见,细胞质极少、边界欠清晰;部分区域肿瘤细胞可见微小钙化灶、Homer-Wright菊形团结构和不典型的Flexner-Weinsteiner菊形团结构.免疫组织化学染色肿瘤细胞突触素、嗜铬素A 表达阳性;胶质纤维酸性蛋白、神经元核抗原表达阴性;Ki-67 抗原标记指数约20%.手术后随访6 个月,肿瘤无复发.结论 松果体母细胞瘤是临床少见的发生于松果体实质的幼稚分化肿瘤,以20 岁以下青年人高发,呈高度恶性,患者预后不良.     

脑室内伸长细胞型室管膜瘤的临床病理学特征:病例报告并文献综述

目的 探讨脑室内伸长细胞型室管膜瘤的临床病理学特征.方法 对1例右侧侧脑室内伸长细胞型室管膜瘤患者的临床、影像学、病理学和免疫组织化学特征进行回顾性分析,并复习相关文献.结果 患者临床表现为无明显诱因的头痛,呈进行性加重;MRI检查提示右侧侧脑室内囊实性病灶.经手术完全切除,大体组织呈鱼肉样,约2 cm×3 cm×1 cm大小,部分区域脑组织呈沙砾感.组织病理学检查长梭形肿瘤细胞呈单极或双极伸长,由簇状梭形细胞形成的细胞核密集区及细胞突起呈束状排列的纤维样无核区构成,未见核分裂象及坏死灶,围绕血管分布形成血管周围假菊形团;部分区域可见血管壁玻璃样变和钙化小体.免疫组织化学染色肿瘤细胞胶质纤维酸性蛋白、S-100蛋白、波形蛋白、巢蛋白和神经微丝表达阳性;上皮膜抗原呈局灶性核旁点状阳性反应;突触素和神经元核抗原表达阴性;MIB-1标记指数约为0.50%.文献报道国外29例伸长细胞型室管膜瘤,其中发生于脑室内6例,组织病理学和免疫组织化学特征与本文病例基本一致.电子显微镜观察肿瘤细胞呈室管膜细胞的典型特征,包括细胞突起内可见大量的中间纤维丝、明显的细胞间连接、大量位于细胞表面的纤细的微绒毛以及微绒毛构成的小管状结构.结论 伸长细胞型室管膜瘤是一种较少见的起源于室管膜伸长细胞的室管膜瘤亚型,组织病理学上应与其他由梭形细胞组成的神经系统肿瘤相鉴别,如毛细胞型星形细胞瘤、纤维型星形细胞瘤、神经鞘瘤和孤立性纤维性肿瘤等,免疫组织化学染色及电子显微镜下的特征性改变有助于诊断与鉴别诊断.     

毛细胞型星形细胞瘤

研究背景毛细胞型星形细胞瘤为好发于儿童和青少年的低级别胶质瘤,其中发生于小脑者(WHOⅠ级)的组织形态学呈典型的毛细胞型星形细胞瘤表现。本文报告1例小脑毛细胞型星形细胞瘤患儿的临床表现、影像学和组织病理学特征及其与其他中枢神经系统肿瘤之鉴别要点。方法与结果女性患儿,8岁。临床表现为间断性头痛伴呕吐。MRI显示左侧小脑半球、小脑蚓部类圆形占位性病变,病灶内信号不均匀。术中可见肿瘤组织质地柔软,血运较差,呈胶冻状。肿瘤细胞胞核呈圆形或卵圆形,胞质两端突起呈发丝样,围绕血管排列;部分区域肿瘤细胞胞核伸展呈长梭形束状致密排列或疏松星网状排列,除具有典型毛细胞型星形细胞瘤病理表现外,血管异常丰富,且Rosenthal纤维和嗜酸性颗粒不明显。肿瘤细胞弥漫表达胶质纤维酸性蛋白、突触素、波形蛋白和P53,不表达细胞角蛋白、神经元核抗原和神经微丝蛋白,Ki-67抗原标记指数为2%~5%;血管内皮细胞表达CD34、散在表达CD68。结论毛细胞型星形细胞瘤好发于小脑,肿瘤组织中无明显Rosenthal纤维和嗜酸性颗粒有助于诊断,但不是诊断的必要条件;应注意与毛细胞黏液型星形细胞瘤、血管中心型胶质瘤和胚胎发育不良性神经上皮肿瘤等相鉴别。     

大脑胶质瘤病的临床病理学特征：病例报告及文献综述

目的探讨大脑胶质瘤病的临床病理学特征。方法对1例大脑胶质瘤病患者的临床表现、影像学、组织病理学和免疫组织化学特征进行回顾性分析,并且复习相关文献。结果男性患者,24岁。临床表现为发作性黑蒙和发作时意识丧失性癫瘸症状,以及随后出现的不能缓解的剧烈头痛。MRI显示左侧颞顶叶．基底节区弥散性不规则稍高信号,局灶信号不均匀,无明显占位效应;MRS显示病灶区Cho／NAA比值明显升高。手术切除部分左侧颞叶及海马组织,光学显微镜下观察肿瘤细胞呈轻至中等密度增生,弥漫性浸润;呈星形胶质细胞样形态,胞核为长梭形或纺锤形,染色质轻度深染;核分裂象罕见;未见微血管增生和坏死;肿瘤细胞排列形成明显的继发性结构,包括软脑膜下和室管膜下肿瘤细胞密集生长、血管周围肿瘤细胞聚集及神经元卫星现象等;灰质与白质分界不清,但神经元分布结构基本保留。免疫组织化学染色肿瘤细胞胶质纤维酸性蛋白和S-100蛋白表达阳性,少突胶质细胞系转录因子-2、突触素和神经元核抗原表达阴性;TP53过表达,约8％;Ki-67抗原标记指数约为10％。结论大脑胶质瘤病为临床少见、可累及多个脑叶的弥漫浸润性肿瘤,影像学上无明显占位效应,MRI和MRS检查可提示诊断。肿瘤细胞弥漫性浸润并形成明显的继发性结构,需与多中心,多灶性胶质瘤和脱髓鞘病变等相鉴别。TP53和Ki-67抗原标记指数可资与非肿瘤性病变相鉴别。     

Diffusion-weighted MR imaging and pathologic findings in adult cerebellar medulloblastoma

OBJECTIVES, MATERIALS AND METHODS: The authors present the diffusion-weighted MR imaging and pathologic findings in two adult patients with cerebellar medulloblastoma. RESULTS: Both presented with a vermian mass of the posterior fossa with low signal on SE T1 weighted images, and moderate enhancement of the mass after gadolinium injection. The tumors were of high intensity on diffusion-weighted images with low ADC value. The ADC values (x10(-3) mm2/s) were respectively 0.60 +/- 0.06 and 0.59+/-0.11 (tumor), and 0.65 +/- 0.04 and 0.67 +/- 0.07 (cerebellar white matter). Tumors were highly cellular and composed of densely packed small round cells with hyperchromatic nuclei and scanty cytoplasm. CONCLUSION: diffusion-weighted MR imaging may be useful for the diagnosis of cerebellar medulloblastoma, due to their high cellularity and high nuclear-to-cytoplasmic ratio.     

Medulloblastoma with lipidized cells versus lipomatous medulloblastoma

BACKGROUND: Lipomatous medulloblastoma is a recently identified clinicopathological entity, characterized by areas of lipomatous differentiation, manifestation in adults, and apparently by a favorable prognosis. MATERIAL AND METHODS: In our series of medulloblastomas of adults and children we have found lipidized cells within the tumor in 6 out of 78 cases of adults and in 8 out of 44 cases of children. In 3 adult cases and 3 children cases, lipidized cells were particularly numerous and clustered. RESULTS: Neuronal differentiation was found in 4/6 cases; no case showed GFAP-positive tumor cells. Lipidized cells were constantly immunopositive for vimentin and some of them also for KP-1 and CR3/43. The proliferation potential was evaluated by the immunohistochemical demonstration of MIB-1; MIB-1-labeling index (LI) ranged from 20.8% to 40.5%. No case survived longer than 7 years after diagnosis and postoperative radiotherapy. CONCLUSION: The present 6 cases of heavily lipidized medulloblastoma are not uniform as for age of occurrence, proliferation potential and survival. They do not share the clinical and pathologic features of "lipomatous medulloblastoma". Therefore, the finding of large numbers of lipidized cells in a medulloblastoma does not authorize to diagnose the tumor as "lipomatous medulloblastoma", for which a favorable clinical prognosis is foreseen.     

Spontaneous and ethyl-nitrosourea-induced medullomyoblastomas in cerebellar vermis defect (CVD) mutant rats

A 26-week-old female cerebellar vermis defect (CVD) rat, a mutant with cerebellar vermis defect and cerebellar dysplasia, developed a brain tumor about 10 mm in diameter. Histopathologically, the tumor consisted of diffuse proliferation of small round to ovoid cells with hyperchromatic nuclei, occasionally containing round to strap-shaped myoblastic cells. Immunohistochemically, the small round cells expressed neuron-specific enolase and synaptophysin, indicating neuronal differentiation; myoblastic components reacted to desmin, myoglobin, and vimentin. Based on these findings, the case was diagnosed as a medullomyoblastoma (MMB). Furthermore, two cerebella tumors in CVD rats, which were induced by transplacental application of ethyl-nitrosourea, showed histopathology similar to the aforementioned case. MMB is a very rare tumor in humans and animals; thus, it is noteworthy that MMBs developed in CVD rats, involving the dysplastic cerebellum with abnormal migration of external granule cells. Received: 10 May 1999 / Revised, accepted: 29 June 1999     

Fourth ventricle neurocytoma with lipomatous and ependymal differentiation

We report the case of a 4-year-old girl with a fourth ventricle tumor diagnosed as a cerebellar liponeurocytoma which recurred, showing ependymal differentiation, 14 months after surgery. Magnetic resonance imaging at initial presentation revealed a large mass in the fourth ventricle, and histology showed a neoplasm characterized by a combination of well-differentiated neurocytes and cells resembling adipocytes. The tumor recurrence was histologically identical to the original tumor in some regions, but with fewer adipose-like cells, while other areas presented an endocrine architecture with oligo-like or pleiomorphic cells, and rosette-like arrangements of tumoral cells were seen around the thin vessels, with features similar to cellular ependymoma. The cells in the liponeurocytoma areas expressed synaptophysin, chromogranin A, and epithelial membrane antigen. Glial fibrillary acidic protein was expressed in some dispersed tumoral cells, in lipidized tumoral cells, and in reactive astrocytes. Cytokeratin was focally expressed in the ependymal region of the recurrence. The immunophenotype of our case, with glial, ependymal, and neuronal or neuroendocrine markers, suggest a neurocytoma with lipomatous and ependymal differentiation. This tumor resembled those derived from circumventricular organs. Its localization in the area postrema region led us to hypothesize that it may be derived from this circumventricular organ.The first two authors contributed equally to this work     

Melanocytic medulloblastoma with ganglioneurocytomatous differentiation: A case report

Melanotic or melanocytic medulloblastoma is a rare variant of medulloblastoma, especially when the tumor shows advanced neuronal differentiation. We report a case of this tumor, which developed in the cerebellar vermis in an 8‐year‐old girl. Initial biopsy specimens were identified as classical medulloblastoma with a high MIB1 index. Surgical removal of the tumor was performed after chemo‐radiotherapy, and black pigments were noticed on the tumor surface. Histologically, the tumor was composed of classical medulloblastoma with the presence of pigmented epithelial cells forming tubules and clusters. Immunohistochemically, the pigmented tumor cells were positive for S100 protein, HMB45, and MART1, indicating that the pigments were derived from melanosomes, and these features were compatible with melanocytic medulloblastoma. Interestingly, some of the non‐pigmented or amelanotic tumor cells were also positive for HMB45 and S100 protein. Although the tumor showed an unusual cell combination, it was distinguished from atypical teratoid/rhabdoid tumor (AT/RT) by nuclear expression of INI1/BAF45 protein. The tumor also possessed ganglion‐like cells within the neuropil matrix, which resembled small mature ganglion cells, and was consequently designated as ganglioneurocytoma. The melanotic medulloblastoma and part of the ganglioneurocytomatous area were fused with each other. Hence, the present case provides new information indicating that melanocytic medulloblastoma differs from AT/RT, and that it can exhibit advanced neuronal differentiation. In addition, reduction of the tumor MIB1 index was observed after chemo‐radiotherapy.     

Melanotic medulloblastoma

Summary A melanotic medulloblastoma is reported with electron microscopic and immunohistochemical findings. The cerebellar tumor had seeded through the cerebrospinal fluid to cerebrum and spinal cord, spread through the dura, and metastasized to the lungs. It consisted of (i) anaplastic cells with slight neuronal differentiation, but without the fibrillary background of neuroblastomas, and (ii) epithelial islands pigmentes with melanin. The latter participated in the spread through the dura. Electron microscopy revealed in the pigmented cells tight junctions and oculo-cutanous melanin, including premelanosomes. The anaplastic cells had undistinguished organelles and only small junctions. On immunohistochemistry, the cytoplasm of the anaplastic cells was positive for neuron-specific enolase and neurofilament, and some of the nuclei were positive to S-100, confirming neuronal differentiation. The cells did not stain for glial fibrillary acidic protein, carcinoembryonic antigen, cytokeratin, alpha fetoprotein, vimentin, and epithelial membrane antigen. The melanotic cells were negative to all reagents tested, even to S-100 protein. The presence of oculo-cutaneous melanin and of neuronal elements indicate a neuroectodermal or neural crest origin.Supported by a grant from the B. C. Medical Services Foundation, Vancouver Foundation     

Medullomyoblastoma: a histological, immunohistochemical, ultrastructural and molecular genetic study

Medullomyoblastoma is a rare variant of medulloblastoma containing myoblastic elements. A 9-year-old boy developed a cerebellar syndrome and signs of increased intracranial pressure, the cause of which was a tumor of the cerebellar vermis measuring 7 × 4.5 × 4.5 cm. Morphologically the tumor largely consisted of a medulloblastoma component but displayed glial, myoblastic and ganglionic differentiation on light microscopic, immunohistochemical and ultrastructural examination. The non-enhancing rim of the tumor on magnetic resonance imaging showed extensive ganglionic differentiation. The tumor did not express bcl-2, c-myc, or c-erb-B2 oncoproteins and was negative for the p53 gene product. On molecular genetic studies, the tumor did not show allelic loss on chromosome loci, frequently altered in medulloblastomas, such as 17p, 1q and 9q. Received: 21 April 1997 / Revised, accepted: 23 September 1997     

Lipidized giant-cell glioblastoma of cerebellum

Glioblastoma multiforme is recognized rarely in the cerebellum. We describe a peculiar case with lipid accumulation in giant tumor cells, possibly the second example so far reported in this unusual location. A 46-year-old man with a 5-month history of headache, vomiting, dizziness and instability of gait, was found to have on magnetic resonance imaging an expanding mass situated deep in the left cerebellar hemisphere. The lesion was hypointense in T 1- and hyperintense in T2-weighted images, had poorly defined borders, peripheral edema and annular foci of contrast enhancement. Eight months after subtotal removal and radiotherapy, control MRI showed tumor recurrence with aggressive features. The patient was alive 15 months after operation but follow-up was eventually lost. Histologically, the tumor showed marked pleomorphism, with many giant cells characterized by finely vacuolated cytoplasm strongly suggestive of lipid accumulation. There were few, sometimes atypical mitotic figures and foci of endothelial proliferation. The tumor cells were strongly positive for GFAP, vimentin and S100 protein, all of which stressed the foamy appearance of the giant cells. About 15% of nuclei were positive for Ki-67. We considered the case to be a so-called lipidized glioblastoma, first recognized as a subtype by Kepes and Rubinstein [1981]. Differential diagnosis with anaplastic pleomorphic xanthoastrocytoma is discussed.     

Morphophenotype of medulloblastoma in children and adults. The size of nuclei

OBJECTIVE: Uniform cells with round, regular nuclei characterize the typical histologic aspect of medulloblastoma. Enlargement of nuclei distinguishes the large-cell medulloblastoma variant and is associated with a poor prognosis in pediatric medulloblastomas. The aim of the present study was to compare the size of nuclei between pediatric and adult medulloblastomas by a morphometric analysis. MATERIAL AND METHODS: In 79 neurosurgical specimens of cerebellar medulloblastomas, the maximum nuclear diameter of the largest nuclei was measured. Measurements were performed with a digital-image analysis system. The measure of the maximum diameter was chosen in order to reduce the split cell error. RESULTS: The difference between the mean values in children and adults was statistically significant (p = 0,001). The distribution of maximum values measured in each case had two distinct peaks in the two age groups, in 3.5% of adult cases and in more than 30% of pediatric cases the maximum nuclear size was superior to 12 microm. CONCLUSIONS: The present results show that nuclei of tumor cells in pediatric medulloblastomas are larger than those in adult medulloblastomas and confirm that the phenotype of medulloblastoma is different in the two age groups. Distinct genetic events can, thus, underlie medulloblastoma in childhood and adult age, the prognostic role of genetic variables can differ by age.