Cystic lesions associated with intracranial meningiomas.

Three unusual cases of large, peritumoral cystic lesions associated with intracranial meningiomas are reported. In each case, the cyst caused difficulty in the interpretation of the computed tomogram when the latter was considered as a diagnostic test by itself, but the composite information obtained from the clinical history, cerebral angiography, and a radionuclide brain scan led to the correct preoperative diagnosis. The cyst was extrinsic to the tumor and contained xanthochromic fluid with a high protein content. The cyst wall consisted of brain parenchyma that showed glial cell proliferation (confirmed by the presence of glial fibrillary acidic protein by immunoperoxidase staining).