Intraoperative management of cystic meningiomas.

Cystic meningiomas are uncommon tumors that are easily confused with metastatic or glial tumors with cystic components. We report on our experience of intraoperative findings and management of peritumoral cyst wall and cyst fluid in cystic meningiomas. We reviewed all the meningiomas operated on at our department in a 3 1/2-year period (January 1998 to June 2001). Pathological and intraoperative findings of cystic meningiomas compared to noncystic meningiomas are examined. There were 111 cases of intracranial meningiomas operated on, including seven cystic meningiomas (6.3%). In six cases, we found peritumoral cyst configurations. The tumor locations of cystic meningiomas were the cerebral convexity and sphenoid ridge. One peritumoral cyst formation had meningioma cells in the cyst wall. Cytologic examination of the cystic fluid displayed the presence of meningiothelial cells in one case. In one case, intraoperative findings and pathological examination provided the diagnosis of two differently located meningiomas in one cyst configuration, its walls lined by clear arachnoid. Four of the seven cases had peritumoral cystic meningiomas of the atypical type according to the WHO classification. One case with intratumoral cyst configuration was associated with the anaplastic type (WHO degrees 3). Intraoperative biopsies and histopathological studies of the cyst wall are recommended in peritumoral cystic meningiomas. Our observations suggest that cystic meningiomas have the potential to spread through cystic fluid to the cystic wall in peritumoral cyst configuration. The follow-up intervals should be short in cystic meningiomas.