This is most likely a case of WHO grade II cellular ependymoma - age of patient, anatomic location of tumor, high cellularity, perivascular pseudorosettes (most prominent in Figures 1 and 2), nuclear uniformity, relatively circumscribed tumor borders, and low MIB-1 labeling index. The immunohistochemistry findings are somewhat confusing, but most of them are anyways. I suggest you add EMA stain to see the paranuclear, dot-like cytoplasmic immunoreactivity in neoplastic cells often seen in ependymomas.

 从形态上及发病部位来看，首先考虑室管膜瘤，富于细胞型（ WHO  II 级）。从免疫表型上看，似乎中枢神经细胞瘤也要考虑，但中枢神经细胞瘤发生于第四脑室较少见，而且本例肿瘤间质血管也不太象中枢神经细胞瘤，若要诊断室管膜瘤，加染EMA，免疫表型多一个证据支持。

 EMA表达很局灶，但确实是胞浆点状着色；只是SYN表达很强，有点奇怪。

Ihave no doubt this is WHO grade II cellular ependymoma of the fourth ventricle. 

 富于细胞型室管膜瘤伴神经细胞分化（WHO2级）

 室管膜细胞瘤没问题,分型学习一下!

 室管膜瘤syn会强阳性表达吗？

 室管膜瘤 形态很典型

只是免疫组化很奇怪 学习了