Clinical and histopathological analysis of cystic meningiomas.

Between 1993 and 2003, we treated 21 patients with cystic meningioma (of 365 with meningioma, 5.5%). We grouped these patients according to classifications by Nauta and Rengachary and analyzed them by gender, age, tumor location, clinical manifestations, MRI features and histopathology. The mean duration of symptoms was relatively short at 1.6 months. There were five atypical and 16 benign meningiomas on histopathology. In type I and II cystic meningiomas, with intratumoral cysts, all cyst walls enhanced on MRI and had tumor cells in the cyst wall on histopathology. In type III and IV cystic meningiomas, with peritumoral cysts, the cyst wall did not enhance on MRI and only one case (type III) had tumor cells in the cyst wall on histopathology. We suggest that when the cyst wall shows contrast enhancement on imaging, the cyst wall should be completely removed at surgery. If there is no contrast enhancement, multiple biopsies of the cyst wall should be taken to assess the presence of tumor cells in the cyst wall.