Correlation of clinical and biological parameters with peritumoral edema in meningioma

Peritumoral edema (PTE) in meningioma occurs variably and can adversely affect the clinical course. Moreover, the etiology of PTE in meningioma is not well documented. To examine possible correlations with PTE, the authors investigated the clinical parameters and the expressions of vascular endothelial growth factor (VEGF), matrix metalloproteinases (MMPs), and their inhibitors (TIMPs) in 20 meningiomas. The estimation of tumor volume (VT) and edema volume (VE) was done using Osiris software with magnetic resonance images and the edema index (EI) was calculated. The expression of VEGF, MMP, and TIMP were estimated in all 20 meningiomas by immunohistochemical staining. Western blotting, zymography, and laser densitometry. Tumor location was closely related with PTE. Meningiomas of the frontal lobe or the frontotemporal base had large PTEs, whereas those of the occipitoparietal lobe, posterior fossa or petroclivus were small. The level of VEGF expression bore correlation with the extent of PTE but not with histologic malignancy. MMP-2 and -9 were detected in 100% of meningiomas by zymography. The levels of MMP-9 were significantly elevated in moderate to severe edema (EI > 1.0) group (p < 0.05) whereas those of MMP-2 were elevated in minimal to mild edema (EI < 1.0) group. TIMP-1 and -2 were detected in 19 (95%) and 12 (60%) of meningiomas respectively and their presence had no significant correlations statistically with PTE between two groups (p = 0.190 and 0.089, respectively). Meningiomas with severe PTE expressed high levels of VEGF and MMP-9 and low levels of MMP-2. The expression of MMP-2, -9, and TIMPs as well as VEGF in meningioma suggests that they are strongly related with the presence of PTE in meningiomas, and that they might play the important role in the formation of PTE in meningiomas.