Meningiomas associated with large cysts with neoplastic cells in the cysts walls. Report of two cases.

Two adults presented with frontal lobe masses. As visualized by computerized tomography, both lesions were large cysts with contrast-enhancing mural nodules and enhancing circumferential rims. En bloc resections of the mural nodules and cyst walls were performed. Pathological evaluation of each nodule disclosed a meningioma, and neoplastic cells were found in the distant cyst walls. Although the walls of large cysts associated with some meningiomas have been composed of reactive glia or collagen, the neoplastic character of the cysts in the present cases underscores the need for resection and careful pathological evaluation of the large cysts associated with meningiomas.