1/30/2007 Case 2: Meningioma with atypical and possible rhabdoid features, favor WHO grade 2

Clinical History:

A 40 year old man with a large extra-axial left parietal mass.

Diagnostic Notes:

The distributed H&E-stained slide showed a dural-based neoplasm with the overall pattern of a meningioma . In areas there were sheet-like growth patterns, there were occasional mitotic figures, and there were scattered large pleiomorphic nuclei among the more ordinary meningioma cells. Some of the tumor cells had small to medium-size more or less round cytoplasmic eosinophilic inclusions which displaced the nuclei and gave those cells a rhabdoid appearance . There was no demonstrable brain invasion. Dr Sharer showed, immnunostains which demonstrated that the tumor cells had some immunoreactivity for EMA; rare cells were desmin-immunopositive . The inclusions were not consistently positive for desmin. In some ways, as Dr Sharer commented, these tumor cells had some resemblance to the gemistocyte-like meningioma cells in the case shown by Dr Miller in November. The consensus was that this was an Atypical Meningioma (WHO Grade II). There
was discussion as to how much of a tumor had to have rhabdoid cells in order to call the tumor a Rhabdoid Meningioma, which the WHO regards as a Grade III
tumor ; all present agreed that this example did not have enough such cells to merit that diagnosis , but that the mitdtic activity alone was enough ·to call this Atypical .

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