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Washington University Experience | NEOPLASMS (MENINGIOMA) | Anaplastic | 26A5 Meningioma, anaplastic & Chondrosarc (Case 26) H&E 6.jpg
In other areas (26A1, arrow), large irregular islands of metaplastic cartilage, resembling chondrosarcoma, predominate. A few small foci of bony metaplasia are also noted. Mitotic figures are readily identified in excess of 25/10/HPF. Brain invasion is identified in two areas. Supporting an origin from meningioma, some areas have strong resemblance to the patient's previously resected tumor which has a greater preponderance of meningeal whorls, increase cytoplasm and mitotic activity of an atypical meningioma. In this residual/recurrent meningioma, the findings of dominant sarcomatous histology and a mitotic index > 20/10 HPF support the diagnosis: Anaplastic meningioma, WHO grade III with sarcomatous features.
