びまん性病変―神経膠腫/膠芽腫と辺縁系脳炎

Diffuse cerebral lesions：glioma and limbic encephalitis

gliomaは，一見して明らかに脳腫瘍に見える，脳腫瘍以外の鑑別診断が特に挙がらない症例も多いが，血管障害，炎症・脱髄性疾患や，なんらかの脳炎脳症，感染症，代謝性疾患，脳形成異常などとの鑑別が難しい症例もしばしばあると思われる。

Gliomas usually appear obviously to be brain tumors. However, they may sometimes be difficult to differentiate from other non-neoplastic diseases such as cerebrovascular lesions, inflammatory demyelinating diseases, encephalitis, encephalopathy, brain infections, metabolic disorders, and brain malformations. Gliomas sometimes present with medial temporal lobe lesions；therefore, in some of these cases, differentiation from limbic encephalitis may be challenging. Limbic encephalitis is often associated with abnormalities in the limbic system, involving the hippocampus, amygdala, and the area around them. However, since there are several causes of limbic encephalitis, imaging diagnosis of specific cause is difficult in many cases. We present two cases of malignant diffuse astrocytic gliomas, located in the temporal lobe, which mimicked limbic encephalitis and a metastatic tumor, respectively, two cases of limbic encephalitis presenting with characteristic imaging findings and background, and a case of cryptogenic new-onset refractory status epilepticus（C-NORSE）which were difficult to distinguish from limbic and striatal encephalitis. We present the imaging and clinical findings that may prompt appropriate imaging diagnoses of these cases, along with some searches for literature.