MATERIAL and METHODS: The neuropathology archive and hospital records of 75 patients with AM who underwent surgery in our institution between 2010 and 2019 were retrospectively reviewed. The pathological revision was performed according to the 2016 World Health Organization (WHO) criteria. Other clinicopathological parameters, such as age, gender, tumor location, preoperative tumor size, degree of resection, Psammoma body, nuclear atypia, main histological pattern, Ki67 labeling index (LI), radiotherapy, and dura and bone invasion, were also analyzed. Statistically, univariate and multivariate analyses were assessed to determine their potential impact on recurrence-related prognostic factors.

RESULTS: Recurrence occurred in 20 patients. The mean PFS and follow-up time were 38.9 and 44.8 months, respectively. In univariate analysis, clinical and pathological features such as age of ?55 years, female sex, skull base tumor location, larger preoperative tumor size, increased mitotic count, small cells, hypercellularity, sheeting, necrosis, and dura and bone invasion were remarkable in patients with recurrence, but were not statistically significant. In multivariate analysis, increased mitotic activity and brain invasion either considered alone or combined were significantly associated with PFS. Nuclear atypia was also not associated with both tumor recurrence and PFS. However, clinical features did not significantly influence the PFS.

CONCLUSION: This study found that recurrence could not be predicted by the presence of any of the clinicopathological features of AMs. We believe that molecular variables determined through routine neuropathological analysis will be needed in the future. Keywords : Atypical meningioma, Recurrence, Progression-free survival, Prognostic factors