Clear cell meningioma, an uncommon variant of meningioma: a clinicopathologic study of nine cases

Aims: Clear cell meningioma (CCM) is an uncommon variant of meningioma, which affect younger patients, occur more often in spinal or cerebello pontine locations and shows a higher recurrence rate. Only few case reports have been described in the literature. The study has been undertaken to document the clinicopathological features of nine cases of CCM, operated at All India Institute of Medical Sciences during 1998 to December 2005. Methods: Clinical information was retrieved from the records of our Neurosurgery Department. The cases were stained with H&E, periodic Acid Schiff (PAS) with and without diastase. Immunohistochemistry for pancytokeratin, epithelial membrane antigen, vimentin, glial fibrillary acidic protein, and MIB-1 was done in all cases. Results: During a period of 8 years, nine cases of CCM were diagnosed. Age ranged from 10 to 65 years (median age 26.0 years) with female predominance. Most common location was posterior fossa (CP angle). Clinically most of the patients presented with history of headache and features of cranial nerve palsies. The duration of symptoms varied from 3 to 60 months (mean 16.7 and median of 4 months). Radiologically lesions showed homogenous enhancement and were isointense to brain parenchyma. Histopathologic examination revealed tumor cells to be arranged in sheets with clear cytoplasm and monomorphic nuclei. MIB-1 labeling index (LI) ranged from 2 to 12% with a mean of 9%. Follow up varied from 3 to 84 months (median 36 months) and recurrence was noted in two patients after 2 and 3 years of surgery, respectively, despite their low MIB-1 labeling indices. Conclusions: CCM is a rare variant of meningioma with poor outcome. Less than 50 cases have been described in the literature. Low rate of recurrence and recurrence despite their low MIB-1 LI are some of the features, which needs to be documented. Hence, larger number of cases with adequate follow-up data need to be studied further to establish the clinical significance of this variant.