三角征
三角征常见于累及大脑皮质或皮质-皮质下白质的幕上病灶，以大脑表面为基底，尖部指向大脑深部，呈三角形或楔形，称为三角征。病灶往往边界淸晰，无瘤周水肿，无或有轻微占位效应。
Triangulation is usually seen in the supratentorial lesions involving the cerebral cortex or cortical-subcortical white matter, with the cerebral surface as the base, the apex pointing to the deep brain, triangular or wedge-shaped, known as the triangulation sign. Lesions often have clear boundaries, no peritumor edema, no or slight mass effect.
三角征和瘤内分隔( septations)是胚胎发育不良性神经上皮瘤( dysembryoplastic neuroepithelial tumor,DNT)相对特征性的表现。三角征可能与神经胶质纤维通路放射状分布有关，瘤内分隔可能与瘤内垂直于脑皮质表面的分支状毛细血管有关。
Sepdations are relatively characteristic in dysembryoplastic neuroepithelial tumor (DNT). Triangulation may be related to the radial distribution of glial fiber pathways and intratumoral segregation may be related to the branching capillaries perpendicular to the cortical surface of the brain.
DNT是一种较为少见的良性神经上皮源性肿瘤，由Daumas- Duport等在1988年首先报道并命名，至今报道的病例不多。2000年版世界卫生组织(WHO)神经系统肿瘤分类把DNT归为神经元和混合性神经元神经胶质肿瘤，属WHO分级的Ⅰ级。
DNT is a relatively rare benign neurodermatogenic tumor, which was first reported and named by Daumas-Duport et al in 1988, and few cases have been reported so far. 2000 the world health organization (WHO) classification of nervous system tumors the DNT as neurons and glial tumors, mixed neurons belong to the WHO classification Ⅰ level.
DNT多发生于儿童及青年，90%多在20岁前发病，男性略多于女性。临床表现主要为反复发作的难治性癫痫(复杂部分性发作为主)而且癫痫几乎是其唯一症状。发生癫痫的年龄从刚出生至45岁不等，平均约7岁。多数病例神经系统体征阴性，无斑痣性错构瘤病家族史。DNT好发于幕上，以颞叶最常见，可累及海马，其次为额、顶、枕叶，极少数发生于深部灰质、脑干及小脑。
DNT is most common in children and young people. More than 90% of them develop the disease before the age of 20. Men are slightly more likely than women. The main clinical manifestations are recurrent refractory epilepsy (mainly complex partial seizures) and epilepsy is almost the only symptom. The age at which epilepsy occurs ranges from birth to 45 years, with an average age of about 7 years. Most of the patients had negative neurological signs and no family history of nevus hamartoma. DNT occurs in the supratentorium, most commonly in the temporal lobe, involving the hippocampus, followed by the frontal, parietal and occipital lobes; very few occur in the deep gray matter, brainstem and cerebellum.
影像上DNT通常表现为边界淸晰的、瘤周无水肿、无或有轻微占位效应的皮质或皮质-皮质下白质内假囊肿样病灶，呈不规则的多结节融合脑回状，或表现为受累脑回不同程度的球样扩张、皂泡状隆起。轻微占位效应表现为邻近脑实质推移及脑沟变窄，极个别病例见瘤周明显水肿及明显占位效应，邻近颅骨可见变形重构。
DNT on images usually showed cortical or cortical subcortical white matter pseudocyst like lesions with clear boundaries, no peritumor edema, no or slight mass effect, showing irregular multinodular fused gyri, or spherical dilatation and soapbubble uplift of varying degrees in the affected gyri. Slight mass effect was manifested by the passage of adjacent brain parenchyma and narrowing of brain sulci, peritumor edema and mass effect were observed in very few cases, and deformation and reconstruction of adjacent skull were observed
CT多数呈低密度，偶见混杂密度，钙化少见，多数无强化，少数可有局灶性强化，有的可见囊变，也有个别病灶呈大块钙化。
CT mostly showed low density, occasionally mixed density, rare calcification, no enhancement in most cases, focal enhancement in a few cases, cystic degeneration in some cases, and massive calcification in some cases.
MR对DNT的诊断有重要作用，多数呈不均匀的长T1、长T2信号，有的可见单个或多个囊状改变或分隔区，呈三角形分布(三角征),或呈圆形或矩形。T1WI偶尔呈混杂信号，可能为黏液样物质或岀血，瘤周一般无水肿或轻度水肿，病灶无强化或轻微强化，若强化也只是病灶周边局限性强化，实体性强化极少见。瘤内可见条索状从边缘向中心延伸的等信号分隔。FLAIR像呈高于脑脊液的偏低信号，周边呈高信号。DWI上呈低信号，表面弥散系数(ADC)值升高。Yamasaki等发现，DNT的ADC值明显高于其他WHO分级Ⅰ级或Ⅱ级的胶质瘤和其他神经元神经胶质肿瘤，而且也明显高于其他神经上皮源性肿瘤，并且ADC值没有重叠。这可能是由于DNT含有较少的细胞成分和较大的细胞外间隙所致。在MRS成像上胆碱和肌酸峰接近正常或稍低，而NAA峰(N-乙酰门冬氨酸)与低级別的星形细胞瘤相比降低不明显，这种代谢改变符合DNT的良性生物学特性。
MR plays an important role in DNT diagnosis, most of them show uneven long T1 and long T2 signals, and some can see single or multiple cystic changes or separation areas, which are triangular in distribution (triangulation), or round or rectangular. T1WI occasionally showed mixed signals, which may be mucus-like substances or bleeds, generally without edema or mild edema around the tumor, lesions without enhancement or slight enhancement, if the enhancement is only peripheral lesion localization enhancement, substantial enhancement is rare. Within the tumor there are bands of isosignal separation extending from the edge to the center. FLAIR has a low signal higher than CEREBROspinal fluid and a high peripheral signal. DWI presented low signal and the surface dispersion coefficient (ADC) value increased. Yamasaki, found that DNT ADC values were significantly higher than those of the other WHO class Ⅰ or Ⅱ glioma and other neurons glial tumors, but also significantly higher than the other neurological tumor incidence, and ADC values without overlapping. This may be due to the fact that DNT contains less cellular components and larger extracellular Spaces. On MRS imaging, the peaks of choline and creatine were close to normal or slightly lower, while the peak of NAA (N-acetylaspartic acid) was not significantly reduced compared with low-level astrocytomas. Such metabolic changes were in line with DNT's benign biological characteristics.
DNT诊断主要依据以下几点：
①发病年龄>20岁(90%);
②长期有癫痼发作史或其他相应受累部位的症状，且药物控制癫痢不理想；
③影像学检査发现边界清晰的病变位于脑叶皮质内，部分侵及皮质下，水肿及占位效应少见，有的病灶内有囊变。增强无强化或出现少数周边性强化，邻近颅骨可见变形重构；
④病理活检符合DNT组织学特点。
正确诊断DNT对临床治疗具有指导意义，但有时候术前、甚至术后病理诊断都非常困难，需要神经科医师、神经放射学家和神经病理学家相互配合才能诊断。手术切除DNT是必要的和唯一的治疗方法，可控制癫痼发作乃至治愈，一般预后良好，不需放疗或化疗，目前复发和恶变都仅见于个例报道。
DNT diagnosis is mainly based on the following points: onset age >20 years old (90%); Have a chronic history of epilepsy or any other symptoms associated with it, and drug control of epilepsy with chronic dysentery is not ideal; (3) Imaging examination found that the well-defined lesions were located in the cerebral cortex, with partial invasion to the cortex, edema and mass effect were rare, and some lesions had cystic changes. There was no enhancement or a few peripheral enhancement, and the adjacent skull was deformed and reconstructed. (4) Pathological biopsy accords with DNT histological characteristics. DNT has a guiding significance for clinical treatment, but sometimes preoperative and even postoperative pathological diagnosis is very difficult, and it requires the cooperation of neurologists, neuroradiologists and neuropathologists to diagnose. DNT has been a necessary and only treatment with surgical resection, thus it has had a good prognosis regarding control of epileptic seizure or cure, and there is no need for radiotherapy or chemotherapy. Currently, relapse and chronic changes have only been reported in single cases.
