This is a difficult case to interpret. From the photos uploaded,  I can tell what this malignant neoplasm is not, but I cannot tell what it is for sure. Many cells have clear or vacuolated cytoplasm, and there are many thick collagenous fibers and sinusoidal vessels between cells. Cells in Figures 18-20 appear somewhat different from the rest. The patient's young age does not present many differential diagnoses, but I can not imagine this being a benign meningioma, hemangioblastoma, pilocytic astrocytoma, desmoplastic infantile ganglioglioma, desmoplactic cerebral astrocytoma of infancy, other types of ganglioglioma, oligodendroglioma, ependymoma or fibrillary astrocytoma. It does suggest hemangiopericytoma. I would need more information (pre-surgical MRI) before I can give an opinion.

 透明细胞型脑膜瘤，2级

 谢谢mjma老师，明日去放射科获取MRI等资料再上传。

 mjma老师，MRI图片很多，挑了几张，如需要还可上传。

Thank you for uploading the neuroimages expeditiously. From them, I see an intra-axial, fairly well cirecumscribed and lobulated, cystic/solid parenchymal tumor without much surrounding edema. This remains a difficult malignant neoplasm to classify and grade. In addition to showing focal cautery artefacts, the photomicrographs show thick and broad collageous fibers and large gaping sinusoidal vessels between neoplastic cells. Large areas of fibrosis and focal calcification are seen. I wonder if more photos of well preserved areas stained by HE would help or not (especially near where photos 18~20 were taken that show cells with more pleomorphic nuclei and no vacuolated cytoplasm). GFAP immunoreactivity seems real and diffuse, but EMA immunoreactivity is questionable. I can safely conclude that this is not a clear cell meningioma, hemangioblastoma, desmoplastic cerebral astrocytoma of infancy, desmoplastic infantile ganglioglioma, and pleomorphic xanthoastrocytoma. Hemangiopericytoma may show clear cells, but it is almost never cystic. Pilocytic astrocytoma remains an important neoplasm to rule out. It can contain many clear cells like in this case, so we have to look for eosinophilic granular bodies, Rosenthal fibers and biphasic growth pattern in any area. An oligodendroglioma is possible, but the blood vessel pattern seen here is not consistent with delicate capillaries seen in oligodendroglioma. This may also be a rare form of glioneuronal tumor that cannot be classified easily. Finally, astroblastoma should be considered in such a young child. It usually would show striking papillary growth in addition to hyalinized fibrosis. So, the bottom line is with the images available so far I DON'T KNOW WHAT THIS IS. It would help to examine all the slides under the microscope to appreciate histopathology first hand. If you have no additional good diagnostic idea, you should consider sending it out for an expert second opinion. Alternatively, scan a few representative HE slides into digital files for telepathology consultation. Hope my discussion helps.

 Thanks for Dr. Ma's detail description and DDx, I would like to put in another DDx, clear cell ependymoma.

Please let us know the final Dx.

 补做CD34、BCL－2、NSE、SYN均为阴性。

 从形态学、免疫标记和影像学表现来看，首先要考虑为透明细胞型脑膜瘤。部分脑膜瘤病例可以表达GFAP。透明细胞型室管膜瘤的好发部位及EMA免疫标记表达方式均不太支持。建议加染PR及PAS。

 考虑透明细胞型脑膜瘤