Enhancing gliotic cyst wall with microvascular proliferation adjacent to a meningioma

Cystic meningiomas are uncommon. Contrast enhancement of the cyst wall of peritumoral cysts on radiological imaging is generally thought to indicate that the wall contains tumor cells. The authors present a patient with a peritumoral cyst that enhanced despite the absence of tumor cells. Histological analysis demonstrated a gliotic cyst wall with numerous microvascular proliferations (MVPs) adjacent to a mixed transitional and angiomatous/microcystic meningioma. Immunoreactivity for vascular endothelial growth factor (VEGF) and its receptor, flt-1, was observed in the endothelial cells of both intratumoral vessels and cyst wall MVPs. Immunoreactivity for tenascin-C was strongly observed within and around the vascular wall of MVPs and in gliotic tissue adjacent to the meningioma. These changes are unusual in the peritumoral brain parenchyma of a slow-growing convexity meningioma and the MVPs may account for the atypical contrast enhancement of the cyst wall despite the absence of tumor cells.