间变型星形细胞瘤( anaplastic astrocytoma)是弥漫浸润生长的恶性星形细胞瘤,成年人多见,好发于大脑半球。肿瘤可由弥漫型星形细胞瘤(WHOⅡ级)演变而来,或者无原始病变而直接形成,其良恶性分级为WHOⅢ级,属于恶性肿瘤。
Anaplastic astrocytoma is a diffuse and infiltrating malignant astrocytoma. It is common in adults and usually occurs in cerebral hemisphere. Tumors can be made of diffuse astrocytoma (WHO Ⅱ) evolved, or without original lesions form directly, the benign and malignant class for the WHO Ⅲ, belong to malignant tumor.
间变型星形细胞瘤较胶质母细胞瘤和弥漫型星形细胞瘤少见,约占全部颅脑肿瘤的4%。但也有报道它的发病率略高于弥漫型星形细胞瘤,约占全部胶质瘤的25%。年龄和性别分布本病好发于35岁-55岁的中年人,男性患者略多。发生部位间变型星形细胞瘤与胶质母细胞瘤的发生部位相同,好发于大脑半球,也可见于丘脑和桥脑,但是极少发生于小脑。
Mesenchymal astrocytoma is less common than glioblastoma and diffuse astrocytoma, accounting for about 4% of all brain tumors. However, its incidence is reported to be slightly higher than diffuse astrocytoma, accounting for about 25% of all gliomas. Distribution of age and sex the disease mainly occurs in the middle aged 35 -55 years old, male patients slightly more. The location of the astrocytoma is the same as that of the glioblastoma. The astrocytoma often occurs in the cerebral hemisphere, and can also be seen in the thalamus and pontine, but rarely in the cerebellum.
临床表现主要包括癫痫和局部定位症状。间变性星形细胞瘤临床预后较差。间变性星形细胞瘤可以通过细胞外间隙和沿白质束扩散,也可通过室管膜和脑脊液扩散。病理大体标本上可见肿瘤呈浸润性生长,与脑组织分界欠清,镜下可见局部细胞生长活跃伴异型性,细胞密度较高,细胞核的非典型性与核分裂多见,血管内皮增生活跃,局部可见坏死。间变性星形细胞瘤相对于低级别星形细胞瘤而言其细胞密度更高,细胞核的非典型性与核分裂更突出。不同于胶质母细胞瘤的是间变性星形细胞瘤缺乏典型的血管增殖和坏死。免疫组化表现:MMP-9(+),TopoII(++),EGFR(+),GFAP(+),PTEN(+)S100(+),EMA(+),VEGF(+)。与弥漫性星形细胞瘤相比,间变性星形细胞瘤Ki-67抗原标记指数升高。
The clinical manifestations mainly include epilepsy and localized symptoms. The clinical prognosis of anaplastic astrocytoma is poor. Anaplastic astrocytomas can spread through the extracellular space and along the white matter tract or through the ependymal membrane and cerebrospinal fluid. The gross pathological specimens showed infiltrating growth of tumor, and the boundary with brain tissue was not clear. Microscopically, local cell growth was active with atypia, and the cell density was relatively high. Atypical and mitotic nuclei were more common, vascular endothelial hyperplasia was active, and local necrosis was observed. Compared with low-grade astrocytomas, anaplastic astrocytomas have higher cell density and more prominent nuclear atypia and nuclear division. Unlike glioblastomas, anaplastic astrocytomas lack typical vascular proliferation and necrosis. Immunohistochemical expression: MMP - 9 (+), TopoII (+ +), EGFR (+), GFAP (+), PTEN (+) S - 100 (+), EMA (+) and VEGF (+). Compared with diffuse astrocytoma, the Ki-67 antigen marker index of anaplastic astrocytoma was increased.
间变性星形细胞瘤在CT平扫时呈低或等低混杂密度、边界不清的较大占位病变,钙化罕见。CT增强扫描,典型者表现为显著不均质强化,以不规则环形强化最常见。
Anaplastic astrocytoma presented a large space-occupying lesion with low or equilow confounding density and unclear boundary on plain CT scan, and calcification was rare. On CT contrast-enhanced scan, the typical patient presented with significantly heterogeneous enhancement, with irregular annular enhancement being the most common.
MR|信号常不均匀,T1WI表现边界不清的低或等低混杂信号,有出血时,出血灶常呈高信号。T2WI病灶中心常呈高信号,周围见等信号环,再向外为高信号水肿带。MRI增强扫描常呈不规则环形强化。DWI肿瘤坏死部分呈低信号,实性部分呈稍高信号。SWI可见边界清楚的低信号出血灶或血管影。多发病灶者,可位于鞍上、下丘脑、海马、海马旁回、额叶、顶叶等多个脑区,其MR表现缺乏特异性。IDH突变型多发生在额叶,不强化者预后较好,而IDH野生型多位于额叶以外区域,明显强化,预后不佳。
MR| signals are often uneven,T1WI shows unclear low or isolow mixed signals, and bleeding foci often show high signals when there is bleeding. In the center of T2WI lesions, there is often high signal, with isosignal ring around, and then high signal edema zone outwards. MRI contrast-enhanced scans often show irregular annular enhancement. The necrotic part of DWI tumor showed low signal, while the solid part showed slightly high signal. SWI shows well-defined low-signal hemorrhagic foci or vascular shadows. Multiple lesions may be located in suprasellar, hypothalamic, hippocampal, parahippocampal gyrus, frontal lobe, parietal lobe and other brain regions, and their MR manifestations lack specificity. IDH mutants are mostly in the frontal lobe, and those without enhancement have a good prognosis, while IDH wild-type mutants are mostly located in areas outside the frontal lobe, with obvious enhancement and poor prognosis.
MRS表现为Cho峰明显升高,Cr峰和NAA峰明显降低。常用Cho/NAA比值和Cho/Cr比值判断星形细胞肿瘤的良恶性,间变性星形细胞瘤Cho/NAA比值通常接近6,而低级别星形细胞肿瘤常在2-4之间。
MRS showed that Cho peak increased significantly,Cr peak and NAA peak decreased significantly. The Cho/NAA ratio and Cho/Cr ratio are commonly used to determine the benign and malignant of astrocytomas. The Cho/NAA ratio of anaplastic astrocytomas is usually close to 6, while that of low-grade astrocytomas is usually between 2-4.
鉴别诊断
根据CT和MRI表现,病灶密度或信号不均匀,呈明显不规则环形强化,典型的间变性星形细胞瘤常比较容易诊断。不典型间变性星形细胞瘤影像学表现缺乏特异性,因此需与颅内其他肿瘤或非肿瘤性病变进行鉴别诊断,包括低级别星形细胞瘤、胶质母细胞瘤、转移瘤、病毒性脑炎和急性期或亚急性期大面积脑梗死。
According to CT and MRI findings, the density or signal of the lesion is not uniform, showing obvious irregular annular enhancement, and the typical anaplastic astrocytoma is often easy to diagnose. The imaging findings of atypical anaplastic astrocytoma lack specificity and therefore need to be differentiated from other intracranial tumors or non-neoplastic lesions, including low-grade astrocytoma, glioblastoma, metastatic tumors, viral encephalitis, and acute or subacute large cerebral infarction.
低级别星形细胞瘤间变性星形细胞瘤较大,常有明显的占位效应,境界不清,可坏死、囊变,强化显著,常呈不规则环形强化;弥漫性星形细胞瘤一般病变较小,占位效应轻,形态规则,呈类圆形,内部液化坏死、囊变较少出现,增强扫描多不强化或仅有轻度强化。MRS:低级别星形细胞瘤的Cho/NAA比值常在2-4之间,而间变性星形细胞瘤的Cho/NAA比值常大于4,PWI:低级别星形细胞瘤呈低灌注,而间变性星形细胞瘤呈高灌注。SWI:间变性星形细胞瘤可见边界清楚的低信号影,而弥漫性星形细胞瘤多无此征象。
The low-grade astrocytoma intergrade degeneration astrocytoma is large, often has obvious space occupying effect, the boundary is not clear, may necrotic, cystic change, the enhancement is significant, often presents the irregular annular enhancement; Diffuse astrocytoma generally has small lesions, light space occupying effect, regular morphology, and a circular shape. There are few liquefaction necrosis and cystic degeneration in the interior, and most of the enhanced scans have no enhancement or only mild enhancement. MRS: the Cho/NAA ratio of low-grade astrocytoma was usually 2-4, while the Cho/NAA ratio of anaplastic astrocytoma was usually more than 4. PWI: the low-grade astrocytoma presented hypoperfusion, while the anaplastic astrocytoma presented hyperperfusion. SWI: anaplastic astrocytomas have well-defined low-signal shadows, whereas diffuse astrocytomas do not.
胶质母细胞瘤典型表现是通过胼胝体前联合和后联合扩展到双侧大脑半球,呈“蝴蝶征”。胶质母细胞瘤一般形态较间变性星形细胞瘤更不规则,肿瘤内坏死常见,增强扫描一般呈显著不规则花环状强化。
Glioblastoma typically extends to both hemispheres of the brain through pre-union and post-union of the corpus callosum, showing the 'butterfly sign'. The morphology of glioblastoma is more irregular than that of the anaplastic astrocytoma. Intracranial necrosis is common.
病毒性脑炎除主病灶外,大多可累及其他脑回,T2WI可见脑回样高信号影呈散在或弥漫性分布,而间变性星形细胞瘤无此表现;增强扫描病毒性脑炎多不强化,而间变星形细胞瘤呈不规则花环状强化;MRS:间变性星形细胞瘤表现为Cho峰明显升高,NAA峰明显降低,ChNA比值通常接近6,而病毒性脑炎Cho峰不增高,Cho/NAA比值通常小于2;临床表现对鉴别很有意义,急性起病,高热,病程短,脑脊液蛋白和细胞数增多都是病毒性脑炎有效的辅助诊断依据
In addition to the main lesions of viral encephalitis, most of them can involve other gyrus. T2WI showed scattered or diffuse distribution of high-signal gyrus shadows, but no such manifestation was found in astrocytoma. Contrast-enhanced scan of viral encephalitis showed no enhancement, while interstitial astrocytoma presented irregular flower ring enhancement. MRS: the Cho peak and NAA peak of anaplastic astrocytoma were significantly increased, and the ChNA ratio was usually close to 6, while the Cho peak of viral encephalitis was not increased, and the Cho/NAA ratio was usually less than 2. Clinical manifestations are of great significance for differentiation. Acute onset, high fever, short course of disease, increased CSF protein and cell number are all effective auxiliary diagnostic basis for viral encephalitis
PS：预后本病患者的预后不佳,间变型星形细胞瘤可恶变进展为胶质母细胞瘤,但其进展的时间间隔有很大差异,平均为2年。
Prognosis in patients with this disease, the prognosis is poor. The anaplastic astrocytoma can malignant progression to glioblastoma, but the time interval of progression varies greatly, with an average of 2 years.
