第348课 （中枢神经）病例探析（094）—菊形团形成的胶质神经元肿瘤

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菊形团形成性胶质神经元肿瘤(rosette-forming glioneuronal tumor,RGNT)是一种罕见的具有明显神经胶质和神经元成分的惰性肿瘤。版WHO中枢神经系统肿瘤分类将其归类于混合性神经元-神经胶质肿瘤,WHOI级。RGNT最常发生于第四脑室,起源于室管膜下,缓慢生长,故肿瘤中心多位于脑室内,易累及导水管、小脑蚓部,但病变也可发生于松果体区、脑干、视交叉、丘脑、侧脑室及脊髓等部位。RGNT发病年龄为6-79岁,男女发病率为1:1.3。在儿童中女性更好发。

Rosette -forming glial neuron tumor (RGNT) is a rare and inert tumor with obvious glial and neuronal components. The WHO classification of central nervous system tumors classified them as mixed neuron-glial tumors,WHOI grade. RGNT most often occurs in the fourth ventricle, originates from the subependymal, and grows slowly. Therefore, the tumor centers are mostly located in the ventricle, which is easy to involve the aqueduct and cerebellum vermis. However, lesions can also occur in the pineal gland, brain stem, optic chiasma, thalamus, lateral ventricle and spinal cord. The onset age of RGNT was from 6 to 79 years old, and the incidence of RGNT in males and females was 1:1.3. Women are more likely to have hair in children.

RGNT的临床症状与肿瘤位置密切相关,多为肿瘤压迫所致,常表现为头痛、共济失调、眩晕。大体病理,肿瘤呈实性、囊实性,部分可呈囊性变伴壁结节,囊性内容物常为胶冻样或淡黄色液体,质地偏软。RGNT可能起源于室管膜下多潜能干细胞,而该细胞具有向神经元和神经胶质细胞分化的潜能,因此肿瘤具有神经元和神经胶质细胞的双相构成形式。肿瘤神经元成分在疏松基质中绕血管形成菊形团和(或)假菊形团是其独特的病理特征,胶质成分为毛细胞型星形细胞瘤,其内含Rosenthal纤维、微囊变、颗粒体、肾小球样血管及微钙化灶,肿瘤内核分裂象和异型性极少。免疫组织化学,菊形团结构Syn呈阳性而GFAP、S-100阴性,星形细胞则GFAP表达阳性,S-100阳性。

The clinical symptoms of RGNT are closely related to the location of the tumor, most of which are caused by tumor compression and are often manifested as headache, ataxia and dizziness. Gross pathology, the tumor was solid, cystic solid, part of the cystic change with wall nodules, cystic content is often gelatinous or yellowish fluid, soft texture. RGNT may originate from subependymal pluripotent stem cells that have the potential to differentiate into neurons and glial cells. Therefore, tumors have a biphasic form of neurons and glial cells. The tumor neuron components form chrysanthemum clusters and/or pseudochrysanthemum clusters around the blood vessels in the loose matrix, the glial components are hair cell astrocytomas, which contain Rosenthal fibers, microcysts, granules, glomerular vessels and microcalcifications, and the tumor core has very little mitosis and atypia. Immunohistochemistry showed that Syn was positive and GFAP and s-100 were negative in chrysanthemum cluster structure, while GFAP and s-100 were positive in astrocytes.

CT表现RGNT通常为四脑室顶部囊实混合性肿瘤,肿瘤实性部分呈稍低密度,囊性成分呈低密度。增强扫描表现为环周性或不均匀强化。出血是一种常见的特征,但CT表现不是很明显。

CT findings of RGNT were generally mixed with cystic and solid tumors at the top of the fourth ventricle, with a slightly lower density of the solid part of the tumor and a lower density of the cystic components. The enhancement scan showed cyclic or heterogeneous enhancement. Bleeding is a common feature, but CT findings are not obvious.

MRI表现肿瘤呈囊实性,多位于第四脑室,可向小脑蚓部、脑干和中脑导水管延伸,常引起阻塞性脑积水;肿瘤实性部分于T1WI呈稍低或等信号,T2WI呈稍高信号。囊性部分T1W1呈低信号,T2WI呈高信号。据报道25%的肿瘤出现不同程度的钙化及“卫星灶”征象,出血亦有报道。增强扫描绝大多数仅表现为轻度不均匀强化或不规则环状强化。多数病变与周围组织边界较清,瘤周水肿轻微或不明显。DWI显示肿瘤无明显扩散受限,ADC偏高,MRS分析发现Cho峰增高,NAA峰虽有降低但不明显, Cho/NAA比值不高,均可见Lac峰及Iip峰提示肿瘤供血不丰富。PWI显示肿瘤实质成分均呈低灌注。SWI显示病灶实质内有点片状低信号影对诊断RGNT具有一定的特异性.

MRI showed that the tumors were cystic and solid, mostly located in the fourth ventricle, extending to the vermis, brainstem and midbrain aqueduct, often causing obstructive hydrocephalus. The solid part of the tumor showed a slightly lower or equal signal on T1WI and a slightly higher signal on T2WI. The signal of T1W1 and T2WI was low and high in the cystic part. Calcification and "satellite foci" were reported in 25% of the tumors. Bleeding was also reported. Most enhancement scans showed only mild uneven enhancement or irregular ring enhancement. Most lesions have clear boundaries with surrounding tissues, and peri-neoplastic edema is slight or not obvious. DWI showed that the tumor had no obvious limited diffusion, and ADC was on the high side. MRS analysis found that Cho peak was increased,NAA peak was decreased but not significant, Cho/NAA ratio was not high, and Lac peak and Iip peak indicated that blood supply to the tumor was not abundant. PWI showed hypoperfusion of tumor parenchyma. SWI showed that there was a patchy low-signal shadow in the lesion parenchyma, which had a certain specificity in the diagnosis of RGNT.

RGNT的诊断要点:好发于儿童及青年女性;中线区,幕下第四脑室周围常见;囊实性占位, 实性部分轻度强化,边界清晰,占位效应轻,常见钙化及出血征象;实性部分DWI弥散不受限, PWI肿瘤呈低灌注。鉴别诊断如下

Diagnosis of RGNT is mainly in children and young women. Midline area, common around the fourth ventricle; Cystic solid space occupying, solid part slightly enhanced, clear boundary, mild effect of space occupying, common calcification and bleeding signs; Solid partial DWI diffusion was not limited, and PWI tumor was hypoperfusion. Differential diagnosis is as follows

髓母细胞瘤发病年龄在5-15岁之间, 好发于小脑蚓部,肿瘤常呈稍长T1、稍长T2信号,增强扫描呈轻中度强化,DWI像弥散受限,ADC值降低,而RGNT通常在DWI像上无弥散受限。

Medulloblastoma occurs between the ages of 5-15 years and is usually found in the vermis of cerebellum. The tumors often show slightly longer T1 and T2 signals, and the enhanced scan shows mild to moderate enhancement, with limited diffusion on DWI image and reduced ADC value, while RGNT is usually not limited in diffusion on DWI image.

室管膜瘤好发于1~5岁之间儿童的第四脑室底部,坏死、囊变多见,增强扫描多为轻中度不均匀强化,常铸型蔓延。而RGNT好发年龄偏大,无铸型改变。

Ependymomas tend to occur in the bottom of the fourth ventricle of children between 1 and 5 years old. Necrosis and cystic degeneration are more common. However, RGNT tends to be older with no casting mold change.

毛细胞型星形细胞瘤多发在10-15岁之间,好发于小脑半球或蚓部,多为伴壁结节的囊性肿瘤,结节强化而囊壁多不强化。虽然RGNT部分为囊实性,但毛细胞型星形细胞瘤壁结节通常强化更明显。

pilocytic astrocytomas are most common between the ages of 10-15 years old. They tend to occur in cerebellar hemisphere or vermis. Although RGNT is partially cystic, hair cell astrocytoma wall nodules are usually more strongly strengthened.

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