gms | German Medical Science

Objective: WHO grade II meningiomas are associated with a higher rate of recurrence after surgical resection compared to WHO grade I meningiomas. This finding might be explained a more diffuse and infiltrative growth. Infiltration of the subarachnoid layer and adjacent brain tissue by extraaxial lesions promotes peritumoral edema formation. The aim of the study was to evaluate preoperative tumor and peritumoral edema volume in adult supratentorial meningioma patients in correlation to histological subtyping (WHO grade I or II).

Method: We carried out a 3D-volumetric assessment of supratentorial meningiomas, all treated surgically between 2007 and 2010. Of more than 200 meningioma patients, 21 were diagnosed as WHO°II meningiomas and had sufficient preoperative MR-imaging available for volumetric assessment. These patients were matched with 27 WHO°I meningiomas, according to age and gender for further analysis. Criteria for volumetric assessment were histological subtyping in either WHO°I or °II meningioma and availability of preoperative MR-imaging with T1 (+ contrast agent) and T2 or TIRM sequences. ROI-based 3D-volumetry was performed using Osirix for Mac V. 5.0, 32-bit. For statistical analysis an unpaired t-test was used as appropriate.

Results: The 48 eligible patients showed a female predominance (n=28, 58%, f:m=1,4:1). Median age at surgery was 62,5 years (range 17-80). Mean tumor volume for WHO grade I meningiomas was 30,01 cc (range 0,8-195 cc) in comparison to the mean peritumoral edema volume of 23,41 cc. For WHO grade II meningiomas a mean tumor volume of 29,99 cc (range 1,5-80,6 cc) with a peritumoral edema volume of 25,22 cc (range 0-166,4 cc) was found. Histological subtyping showed no significant influence on tumor volume (p=0,593) or peritumoral edema volume (p=0,633).

Conclusions: Although WHO grade II meningiomas are suspected to have a higher infiltrative pattern, there is no significant difference in tumor or peritumoral edema volume compared to WHO grade I tumors. Thus, other factors affecting the tumor-brain interface may be involved in edema formation.