Preoperative and Histological Predictors of Recurrence and Survival in Atypical Meningioma After Initial Gross Total Resection Joshua Loewenstern 1 , William Shuman 1 , John W. Rutland 1 , Remi A. Kessler 1 , Karan M. Kohli 1 , Melissa Umphlett 2 , Margaret Pain 1 , Joshua Bederson 1 , Mary Fowkes 2 , Raj K. Shrivastava 1,3 - OBJECTIVE: Atypical (World Health Organization grade II) meningiomas (AMs) have been associated with a sub- stantial risk of recurrence even after complete, gross total resection (GTR). The present study evaluated the clinical and AM tumor histopathological features that might predict for the risk of recurrence and survival within this patient population. - METHODS: The data from 72 consecutive patients who had undergone primary GTR for AM from 2007 to 2016 and corresponding tumor specimens at a single institution were reviewed. The preoperative patient and tumor characteristics were correlated with the post- resection outcomes, including recurrence and 1-year survival. Cox regression models on recurrence-free survival (RFS) and Kaplan-Meier survival estimates were performed. - RESULTS: The overall 1-, 3-, and 5-year RFS estimates for the AM cohort were 100.0%, 82.4%, and 78.1% after resection, respectively. A high mitotic index was an in- dependent predictor of RFS on Cox regression analysis (hazard ratio, 1.26; P [ 0.008), and the tumor volume showed a trend toward a significant association (hazard ratio, 0.93; P [ 0.079). Patient age and the mitotic index were significantly associated with 1-year mortality (odds ratio, 1.11 and 1.36, respectively; P [ 0.028 and P [ 0.045, respectively). - CONCLUSIONS: AM tumors with a high proliferative index showed an increased likelihood of recurrence and short-term survival even after complete GTR. A smaller tumor volume might also have contributed to an increased risk of recurrence for patients with AM. Although other histopathological features were not linked to recurrence or mortality for patients with AM, the biopsy findings can indicate key predictive information, and further molecular analysis might reveal additional prognostic markers. INTRODUCTION M eningiomas are one of the most common primary intracranial tumor in adults, accounting for one third of resected primary brain tumors. 1,2 The World Health Organization (WHO) has classified meningiomas into 3 grades: grade I, benign; grade II, atypical; and grade III, anaplastic. Compared with the most commonly encountered benign menin- gioma, atypical meningiomas (AMs) are more aggressive and have been associated with more rapid disease progression and morbidity, leading to poorer outcomes and decreased survival. 3-9 After the WHO changed the classification system in 2007 such that otherwise benign meningiomas with the presence of brain invasion should be considered atypical, WHO grade II constituted one fifth or greater of meningiomas. 4-6,10 Therefore, the present study restricted the cohort to patients with AM resected after 2007 Key words - Atypical meningioma - Meningioma - Recurrence - Survival - Tumor pathology Abbreviations and Acronyms AM: Atypical meningioma GTR: Gross total resection HPF: High-power field HR: Hazard ratio KPS: Karnofsky performance scale OR: Odds ratio RFS: Recurrence-free survival RT : Radiotherapy WHO: World Health Organization From the Departments of 1 Neurosurgery, 2 Pathology, and 3 Otolaryngology, Icahn School of Medicine at Mount Sinai, New York, New York, USA To whom correspondence should be addressed: Raj K. Shrivastava, M.D. [E-mail: raj.shrivastava@mountsinai.org] Citation: World Neurosurg. (2019). https://doi.org/10.1016/j.wneu.2019.04.069 Journal homepage: www.journals.elsevier.com/world-neurosurgery Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2019 Elsevier Inc. All rights reserved. WORLD NEUROSURGERY -: e1-e9, - 2019 www.journals.elsevier.com/world-neurosurgery e1 Original Article