Clinicoradiological Features of Recurrent Meningioma With High Grade Transformation.

Background/Aim: A minority of grade I meningiomas (MG1s) recur after surgical resection and their progression is associated with high grade transformation (HGT). This study aimed to characterize the clinicoradiological features of recurrent MGs (RMG) with HGT. Patients and Methods: We identified 17 patients diagnosed with MG1 who then underwent surgery for RMG. Patients were categorized into HGT group vs. non-HGT (nHGT) group based on RMG histological grade and clinicoradiological features were comparatively analyzed. Results: HGT was observed in 41.4% of RMGs. Original tumor size was larger in the HGT group and recurrence time interval was shorter. Following recurrence, 57.1% in the HGT group experienced further disease progression, compared to 22.2% in the nHGT group. Conclusion: A considerable HGT rate in RMGs developed after MG1 was observed. Although HGT was not distinguished from nHGT by radiological features, HGT in RMG was associated with larger initial tumor size and shorter recurrence time interval.