[2 Cases of cystic meningioma].

Although meningiomas are usually a solid and firm tumor, some are associated with diagnostically confusing large cysts. The authors experienced two cases of meningioma associated with large cyst (cystic meningioma). The first case was a 20-year-old female. She was admitted because of blurred vision. On admission she was slightly apathetic and showed bilateral papilledema. Computed tomography showed a large area of low density in both frontal regions. CT scan after intravenous contrast enhancement revealed an enhancing mural nodule attached to the falx. At operation, dark-green fluid in an amount of 160 ml from the left cyst and 50 ml from the right cyst was aspirated. The nodular tumor was found attached to the falx. The pathological examination revealed meningotheliomatous meningioma. Neoplastic meningothelial cells were found also in the cyst wall. The second case was a 21-year-old female. She was admitted because of weakness of the left lower extremity. Neurological examination revealed left hemiparesis. Deep tendon reflexes were hyperactive on the left side and there were positive left Babinski and Chaddock reflex. The computed tomography with contrast enhancement showed a large area of low density in the right parietal region with markedly enhancing mural nodule. At operation, 70 ml of xanthochromic fluid was aspirated. The tumor was well-defined, hard and attached to the dura. Histologically the tumor was a typical meningotheliomatous meningioma. The diagnostic value of computed tomography, the pathogenesis of cyst formation and the surgical treatment were discussed. The authors emphasized the important role of computed tomography in the diagnosis of cystic meningioma. Theories were reviewed for the pathogenesis of cyst formation. At operation, not only the mural nodule but also the cyst wall should be removed, because the neoplastic cells are presented in the cyst wall.