越看越不懂了，请各位老师指点。

 我也首先考虑淋巴瘤. 同意xiaohl, CD20,CD45均阴性不能排除淋巴瘤,

应加作更多标记.

 一个很特殊的病例

转移低分化癌、T细胞淋巴瘤、脑膜瘤伴脑实质侵犯是我所能想到的可能。

CD45阴性不能完全除外淋巴瘤，应加作更多标记！

 

 

 CD20,CD45均阴性

  lymphoproliferative disorders

Perivascular collection of atypical cells with medium sized, oval and sometimes elongated nuclei, little cytoplasm, indistinct intercellular borders with focal necrosis in brain parenchyma is seen. Occasional these atypical cells have floret-like nuclei. No granulomas or multinucleated giant cells are seen. My first thought is also lymphoproliferative disorders. The cytology is different from that of the usual large B cell lymphomas in the CNS. Instead, it suggests T cell lymphoma, which is extremely rare in the CNS. Other considerations include metastatic sarcoma, spindle cell carcinoma, and melanoma (unlikely based on cytology). I do not think this is meningioma. Immunohistochemical stains would be very helpful for diagnostic interpretation. I would include CD3, CD45RO (UCHL-1), CD4, CD20, CD79a, AE1, S100, and Cam5.2 in the first round. Interesting case this is!

 瘤细胞体积小，核形圆、或稍不规则，围绕血管生长，可见核分裂，首先考虑淋巴造血系统恶性肿瘤。lymphoma may be the first choice.

白血病浸润？ 

 考虑血管内皮型脑膜瘤

 考虑血管性脑膜瘤