The evaluation of meningioma cases that were diagnosed in KTÜ Faculty of Medicine, Medical Pathology department between 2007-2015,according to the world health organization (WHO) 2007 classification

Meningioma is the most-frequently observed primary tumor of Central Nervous System, which stems from 'arachnoid cap' cells located in the most superficial part of the arachnoid membrane. The meningioma cases that were diagnosed in KTU Faculty of Medicine, Medical Pathology Department between 2007-2015 were evaluated retrospectively according to the World Health Organization (WHO) 2007 Classification in our study. 241 of the 325 cases that were diagnosed with meningioma were female (74,2%); and 84 (25,8%) were male. The ages of the patients varied between 13-89, and the average age was 55,3. The most-frequently observed tumor localizations were cerebral convexity (68%), spinal area (9,8%) and parasagittal area (6,7%). According to histological sub-types, 136 of our cases (43%) were meningothelial, 63 (19,9%) were fibroblastic, and 37 (11,7%) were transitional meningioma. It was determined that 35 (11,1%) of the cases were atypical; and 3 (0,9%) were anaplastic histologic sub-type. According to WHO 2007 Classification, 87,7% of our cases were Grade I meningioma; 11,1% were Grade II meningioma; and 1,2% were Grade III meningioma. In 30,6% of the Grade II meningioma, and in 75% of Grade III meningioma cases, brain invasion was observed. It was determined that the brain invasion was more in male patients. It was determined that the Ki-67 proliferation index average value was 3,34% in Grade I meningioma; 7,54% in Grade II meningioma; and 27,5% in Grade III meningioma; and a statistically significant difference was determined between Grade I and Grade II meningioma. Relapse, which is one of the major complications of meningioma, was determined in 12 of our cases; and 2 cases progresses to Grade II and Grade III meningioma. More relapse was observed in Grade II meningioma when compared with Grade I meningioma. In meningioma, which has generally a good prognosis; mortality rates increase as the tumor level increases. In terms of survival, it has been observed that all of our cases, who were diagnosed with Grade II and Grade III meningioma, are still alive. As a conclusion, this study will be a source for future studies with its statistical data.