室管膜瘤可能性大，需要和脑室外神经细胞瘤（extraventricular neurocytoma）鉴别。

以下是引用xiaohl 在2006-11-2 0:13:00的发言： 这是一例富于细胞的肿瘤,主要由小到中等大的瘤细胞构成,血管丰富,可见血管周假菊形团和室管膜菊形团,散在或成片脂肪样细胞.细胞密度高,但异型性不明显,核分裂相罕见,无坏死. 考虑细胞性室管膜瘤(WHOⅡ级),伴脂肪化生.

同意，但有个问题请教肖老师和各位老师，这个脂肪化生是何种细胞化生而来？脑组织内脂肪化生有何意义？小脑脂肪神经细胞瘤中脂肪成分实质是不是就是化生？谢谢！！

免疫组化结果（不多的几项）：
GFAP 及 Vimentin 为阳性。
EMP 及 S-100为阴性。
我们的意见如xiaohl老师所言：
   颞顶部： 细胞性室管膜瘤伴脂肪化生。

This unusual tumor is listed as a "temporo-parietal" tumor. I wonder whether the tumor is associated with the ventricular wall or not. Also, can you let us know how frequent did you find mitoses? Is the tumor sharply circumscribed and demarcated from the surrounding parenchyma? Or is it infiltrative at the edge?

The neoplastic cells are relatively uniform in size between abundat small but somewhat hyalinized blood vessels with perivascular arrangement, formation of Flexner-Wintersteiner rosettes (Figures 9~12) (http://www.mrcophth.com/ophthalmologyhalloffame/wintersteiner.html), possible Homer Wright rosettes (Figures 5~8) and many vacuolated (probably lipidized) cells. Homer Wright rosettes and Flexner-Wintersteiner rosettes are both seen in PNET (retinoblastoma, pineoblastoma, esthesioneuroblastoma, medulloblastoma, neuroblastoma) ans some cases of better differentiated neuronal tumors. Flexner-Wintersteiner rosette is very similar to true ependymal rosette. Whether there are Homer Wright rosettes is important, for these structures indicate neuronal differentiation. The perivascular arrangement of neoplastic cells suggest pseudorosettes of ependymomas, but similar perivascular arrangement can be seen in papillary glioneuronal tumor and some cases of diffuse fibrillary astrocytomas and pilocytic astrocytomas. I am not entirely convinced that this is an ependymoma based on histoarchitecture and cytology of neoplastic cells.

Lipidized cells can be seen in only a few types of primary CNS tumors - (1) cerebellar and, very rarely, supratentorial (http://www.dustri.com/ze/np/samplecopy/march06/np02086.pdf) liponeurocytomas, (2) ependymomas, (3) meningiomas, and (4) glioblastomas/gliosarcomas. I am not sure how mitotically active the neoplastic cells are. I have not seen dysplastic neurons or large ganglion cells to lend support for a neuronal/neurocytic tumor. With no easily identified mitosis or anaplastic features on the uploaded photos, I suspect this case is still a well to moderately differentiated neuronal (neurocytic) neoplasm. If it is associated with the lateral ventricular wall, it would invite the diagnosis of rare supratentorial liponeurocytoma. In my personal opinion, liponeurocytoma is rare and can potentially occur at any location in the CNS.

I do believe immunohistochemistry would help characterize this enigmatic neoplasm further. I would employ the following antibodies and see what is found - GFAP, EMA, synaptophysin, NSE, and MIB-1 (Ki67). I look forward to seeing photos of your immunostains.

同意mjma老师所言,除了室管膜瘤的考虑外,需要排除神经元肿瘤(liponeurocytoma或脑室外中枢神经细胞瘤)的可能.请加作神经元标记.Syn,NSE,NF,MAP-2,NeuN,上述标记至少要做两个.

因抗体原因,仅补做了二项免疫组化:

1--2#为  NSE ;  3--4#为  Syn. 

1 /2 #  GFAP ;   3 / 4 #  Vimentin  ;   5 / 6 #  EMA  。

    我相信免疫组化能帮助我们进一步解开这个肿瘤的谜团。我会选择GFAP、 EMA、SYN、NSE、MIB-1 (Ki67)的免疫组化，看有何发现。.我期待见到免疫组化图片。

以下是引用shihuaiy 在2006-11-14 23:27:00的发言： 免疫组化图4的vimentin可能图传错了，和图2好像一样。请楼主核实。

 
   没有传错图，可能正好取了同一视野的高倍图。

尽管NSE不是很特异，但弥漫强阳性也说明问题，结合GFAP阳性，至少在免疫表型方面符合Liponeurocytoma。尽管该肿瘤多见于小脑，但文献中也有幕上发生的报道，抑或是脑室外神经细胞瘤伴有脂肪化生也有可能。Vim在类似肿瘤的表达不太了解。感觉此例很有意思，盼望能有一个明确的诊断。