ANDREI IONUT CUCU, MIHAELA DANA TURLIUC, ALEXANDRU CARAULEANU, ION POEATA, CLAUDIA FLORIDA COSTEA, GABRIELA FLORENTA DUMITRESCU, ANCA SAVA CHEMICAL ASPECTS OF PERITUMORAL CEREBRAL EDEMA IN ATYPICAL MENINGIOMAS Aim of this study was to perform a retrospective evaluation of the radiological, clinical and pathological features influencing the occurrence of peritumoral brain edema (PBE) and understanding the responsible chemical mediators involved. We have examined magnetic resonance imaging(MRI), symptoms and pathology for 25 patients with convexity atypical meningiomas (WHO grade II), who underwent surgery at Professor Dr. N. Oblu Emergency Clinical Hospital between 2010 and 2017. We evaluated the possible prognostic factors related to peritumoral edema including: demography (age, gender), pathology (anatomical localization of the tumor, tumor volume, brain invasion, shape of tumor margin), symptoms and neuroimaging characteristics such as high signal intensity of the tumor on T2-weighted images (T2WI), contrast enhancement and heterogeneity. Age, gender, anatomical location of the tumor and brain invasion were not correlated with peritumoral edema. Also, the neuroimaging characteristics (homogeneity, high signal intensity on T2WI, high contrast enhancement) or the presence of motor deficit were not statistically significant regarding the relationship with the edema. Peritumoral edema and irregular tumor margins were statistically significantly (p=0.03). Tumor volume was not associated with the peritumoral edema. We also found other significant statistical correlations of the radiological features, which are worth mentioning: high-contrast enhancement with the age of the patient (p=0.006), high signal intensity on T2WI with tumor volume (p=0.03) and tumor heterogeneity with irregular tumor margins (p=0.002). The results of this study demonstrate that an irregular tumor margin may be an important predictive factor that would influence the occurrence of peritumoral edema in atypical meningiomas.