Clear cell meningioma with histologically aggressive appearance and clinically aggressive behavior: a case report.

Clear cell meningioma (CCM) is an uncommon variant of meningioma, corresponding to WHO grade II. We present a case of CCM with histologically aggressive appearance and clinically aggressive behavior. The tumor demonstrated rapid regrowth and brain metastasis. The histological progression from the ordinal CCM to the atypical area and higher MIB-1 index was observed. We assume that the short time of recurrence and metastasis may result from atypical histological features in our case. If the CCM has a histologically aggressive appearance as in our case, we suggest that postoperative adjuvant radiotherapy should be performed despite total resection of the tumor.