Cystic lesions associated with meningiomas.

Three cases of meningiomas associated with large cysts are reported, and 58 other cases from the literature are reviewed. The etiology of these cysts is analyzed on the basis of surgical and pathological findings. The preoperative diagnosis of large computed tomographic hypodensities associated with meningiomas and the differential features from other cystic tumors are discussed. The surgical aspect of the solid tumor and particularly the absence of a capsule separating the tumor from the cyst are usually decisive in confirming the intratumoral nature of the cyst. In questionable cases a histologic evaluation of the cyst walls may be necessary.