Intracranial clear cell meningioma: a clinicopathologic study of 15 cases

Object Clear cell meningioma (CCM) is a rare histological variant of meningioma. CCM has a high recurrence rate and aggressiveness. In this study, we reviewed our experience in the treatment of the lesion. Methods Here we present a series of 15 patients with intracranial CCM. The clinical data were retrieved from the records of our Neurosurgery Department and the patients’ prognoses were attained by clinic service and telephone. Immunohistochemistry for epithelial membrane antigen (EMA), vimentin, glial fibrillary acidic protein (GFAP), CD10, and S-100 was done, and the MIB-1 labeling index was calculated in all cases. Results The 15 patients included eight males and seven females; the mean age was 34.8 years. The most frequent initial symptoms were headache and hearing loss. The most common location was the cerebellopontine angle (CPA) zone. Eleven patients had total removal and four patients underwent subtotal removal. Histological features of atypia were present in different proportions, from 6.7% to 100%, and six cases accorded with atypia. Three tumors showed brain invasion. EMA and vimentin were 100% positive, and CD10 was 100% negative. GFAP was 87% negative and S-100 was 93% negative. The mean follow-up period was 36.7 months. Three patients with brain invasion all recurred and five cases with atypia recurred. In 11 patients with total removal, six patients recurred. In four patients with subtotal removal, three patients recurred. Kaplan-Maier analysis showed that incomplete surgical resection was significantly associated with recurrence (p=0.001). The MIB-1 labeling index for recurrence was 5.7±2.7% versus 2.8±1.5% for no recurrence (p=0.036). Conclusions CCM is a rare subtype of meningioma, with a tendency to present in younger patients and a propensity to recur. Immunohistochemistry plays a vital role in differentiating CCM from other tumors. Brain invasion, atypia and MIB-1 labeling index are likely to predict the recurrence. The extent of resection might be connected with the prognosis.