Polycystic and ring-shaped intracranial meningiomas

Abstract

Intracranial meningiomas may be associated with peritumoral, unilocular cysts. In two middle-aged women we have recently treated, CT scan revealed ring-shaped and polycystic tumors which proved to be meningiomas. This unusual aspect has previously received scant attention. In the first patient the cysts were intratumoral and the walls consisted entirely of meningiomatous tissue; in the second case the cysts were peritumoral and their connective walls contained scattered nests of tumor cells.

Clinical and MRI Findings in Three Dogs with Polycystic Meningiomas

“…However, it is notable that all three cases described herein were classified as Nauta type II, as were two of the reported cases of polycystic meningiomas in humans. 10 The third reported polycystic meningioma in a human did not describe the cyst location relative to the tumor. 11 The pathophysiology question may be better settled by more detailed investigation of tumor contents and surrounding tissue as further cases of this rare tumor phenotype are discovered.…”

“…More recent uses of the term "polycystic" seem to stem from the multiloculated appearance of the mass on imaging. 10,11 Referred to as the Nauta classification scheme, cysts associated with meningiomas have been classified into four configurations: those located centrally within the tumor (type I), peripherally within the tumor (type II), within the adjacent brain (type III), and at the interface of tumor and brain (type IV). 18 In all three cases described herein, the cysts were located peripherally within the meningioma (Nauta type II) (Figure 3).…”

“…9 Polycystic meningiomas are reportedly even more rare in humans. 10,11 To the best of the authors' knowledge, this report describes the first three cases of polycystic meningiomas documented in dogs.…”