Meninges, Microcystic meningioma

Microcystic meningiomas are a subtype of WHO grade I meningiomas. Radiologically, they may produce abundant vasogenic edema in the surrounding brain, which may be misinterpreted as brain invasion. Microscopically, they are characterized by cystic, cobweb-like changes and loose-appearing architecture. Foci of classical meningioma patterns, such as whorls, are variably present. Degenerative nuclear atypia is often present. Prominent thickened, hyalinized blood vessels may also be present, creating diagnostic overlap with angiomatous meningioma. Like other WHO grade I meningiomas, prognosis is excellent for completely-excised tumours.