Are there any correlations between demographic characteristics, tumor location, and Ki-67 labeling index in intracranial atypical meningiomas (WHO grade II)?

Background/Aim: Atypical meningiomas (AMs) account for about 30% of all meningiomas and it is difficult to predict their behavior. Nevertheless, the identification of protein markers responsible for the regulation of cell proliferation can be helpful. The purpose of this study is to find possible correlations between demographical characteristics of patients with AMs, tumor anatomic location, and intratumoral immunohistochemical (IHC) expression of Ki-67 labeling index (LI). Patients, Materials and Methods: We carried out a retrospective review of 29 patients with intracranial AMs [World Health Organization (WHO) grade II] who underwent resection of AMs at "Professor Dr. Nicolae Oblu" Emergency Clinical Hospital, Iasi, Romania, between January 1, 2014 and December 31, 2016. We searched for their demographic characteristics (age and gender) and tumor location from patients' medical files. The histological slides were reviewed in order to assess the Ki-67 LI. Results: Out of the 29 patients analyzed, 51.72% were females having AMs, with a mean Ki-67 LI of 8.6%, and 48.27% were males with AMs, revealing a mean Ki-67 LI of 8.5%. Considering tumor anatomic location, 82.75% were non-skull base AMs (presenting a mean Ki-67 LI of 8.9%) and 17.24% were skull base AMs (showing a mean Ki-67 LI of 8.2%). Although we did not find any statistically significant correlation between gender, age, tumor anatomic localization, and Ki-67 expression, our study revealed that the mean Ki-67 LI for AMs was 8.7% (ranging from 6% to 15%) and was close to values obtained by other authors. In terms of gender distribution, we have noticed that AMs diagnosed in male patients had a mean Ki-67 LI almost equal to that in female patients even though some studies found Ki-67/MIB-1 LIs significantly higher in male patients than in female patients. Also, we did not find any significant correlation between Ki-67 LI and tumor anatomic location as reported by other studies. Conclusions: Despite the fact that statistically we could not find any significant correlation regarding patients' gender and age, tumor anatomic location, and Ki-67 LI expressed by AMs, IHC detection of Ki-67 antigen remains an important tool in addition to routine histological evaluation, which can be used to predict tumor behavior of meningiomas.