Cystic meningioma: radiological, histological, and surgical particularities in 43 patients.

BACKGROUND: The presence of cysts is a rare occurrence for intracranial meningiomas in adults. We report our experience in a large consecutive series of cystic meningiomas. METHOD: We prospectively collected data for a dedicated database of cystic meningioma cases between January 2004 and December 2011 in two tertiary neurosurgical centers. Studied data included preoperative imaging, surgical records, and pathology reports. RESULTS: Among 1214 surgeries for intracranial meningioma, we identified 43 cases of cystic meningioma, corresponding to an incidence of 3.5 %. The most common localization was the hemispheric convexity (17/43 cases). Twenty-eight patients had intratumoral cysts, nine peritumoral, and five mixed intra and extratumoral. In 29 patients with available diffusion imaging, ADC coefficients were significantly lower in grade II-III tumors compared to grade I (p = 0.01). Complete resection of the cystic components was possible in 27/43 patients (63 %); partial resection in 4/43 (9 %); in 6/43 (14 %) cyst resection was not possible but multiple biopsies were performed from the cystic walls; in another 6/43 (14 %) the cystic wall was not identified during surgery. Cells with neoplastic features were identified within the cyst walls at pathology in 26/43 cases (60 %). All patients were followed-up for 24 months; long-term follow-up was available only in 32 patients for an average period of 49 months (range, 36-96 months). No recurrence requiring surgery was observed. CONCLUSIONS: Cystic meningiomas are rare. Cells with neoplastic features are often identified within the cyst walls. Complete cyst resection is recommendable when considered technically feasible and safe.