Cystic changes and vascular permeability in meningiomas.

A retrospective study of 397 human meningiomas revealed microcystic and cystic changes in about 10% of tumors, predominantly meningiomas of the meningotheliomatous subtype. The biological behavior of these tumors corresponded to those of meningiomas in general, while one tumor singled out from the microcystic variant and separately described as myxomatous meningioma was characterized by a high recurrency rate. Histochemical and immunohistochemical examination with serum proteins of variable size indicated that the microcystic alterations are associated with local vascular permeability disturbances. Hyaline vascular changes and increased numbers of mast cells were further intriguing observations with respect to the pathogenesis of microcyst formation. Possible clinical implications, in particular in regard to the sometimes severe peritumoral edema, are discussed. Since surgical material is insufficient in this respect due to sampling limitations, an unoperated autopsy case is included in this study.