Though no meningothelial whorls, syncytia or psammoma bodies are seen, the intranuclear pseudoinclusions and high-power views in the uploaded photos are consistent with WHO grade III rhabdoid meningioma. Rhabdoid meningioma is a recently recognized but rare variant of meningioma that reportedly has aggressive biologic behavior. Rhabdoid cells in rhabdoid meningiomas are usually seen only focally, a feature similar to chordoid meningioma that makes microscopic examination of all resected tissue the only sure way to rule these two variants out. The minimum quantitative diagnostic criterion (% of tumor areas with rhabdoid cells, or how large an individual area of rhabdoid cells has to be present) for rhabdoid meningioma has not been clearly defined. This is complicated by the fact that some cases of rhabdoid meningioma display rhabdoid cells only in the recurrent tumors. Most rhabdoid meningiomas, however, have areas with characteristic meningothelial features and features of atypical meningiomas (necrosis, prominent nucleoli, high mitotic activity, patternless growth and brain invasion). 

More recently, the prognostic significance of finding rhabdoid cells focally in otherwise benign (WHO grade I) meningiomas has been questioned. In my own experience, neoplastic cells with rhabdoid features can be found very focally in benign meningiomas. I also question whether this very focaly finding is sufficient to upgrade the tumor from WHO grade I to grade III.

Many tumors in or outside of CNS may show cells with rhabdoid features. In the CNS, rhabdoid cells can be seen in atypical rhabdoid/teratoid tumor (AT/RT), primary (and metastatic) leptomeningeal melanoma, choroid plexus carcinoma, large cell/anaplastic medulloblastoma, supratentorial PNET, anaplastic plasmacytoma and glioblastoma. Other than metastatic melanoma, cells in a metastatic poorly differentiated carcinoma or sarcoma may appear rhabdoid. Therefore pertinent clinical history and immunohistochemistry workup are essential before a final diagnosis of rhabdoid meningioma is made.

 学习了。

 学习了

  学习了

 学习了一下。感谢老师们。