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Washington University Experience | NEOPLASMS (MENINGIOMA) | Anaplastic | 2E2 Meningioma, anaplastic (Case 2) MIB 1
Ki-67 labeling index is high, reaching up to ~30% in more epithelioid areas and ~17% in more spindled areas. ---- Ancillary data (not shown): A few clusters of tumor cells with epithelioid morphology are positive for progesterone receptor. ---- FISH revealed deletion of chromosome 1p and polysomy of chromosome 9 in epithelioid areas. In spindled areas, the tumor showed combined deletions of chromosomes 1p and 14q and monosomy of chromosome 9. These genetic alterations are more often seen in higher grade meningiomas. ---- Comment: Although the tumor fails to reach a mitotic rate of >20/10hpf, often used as a separation point between atypical and anaplastic meningioma, the high grade histomorphological features (carcinomatous and sarcomatous areas), high mitotic rate (~17/10hpf) and high Ki-67 labeling index as well as FISH genetic alterations are consistent with anaplastic meningioma WHO Grade III and indicate an aggressive biological behavior.
