Clear cell meningioma: clinical features, CT, and MR imaging findings in 23 patients.

Background: Clear cell meningioma (CCM) is a rare meningioma, with radiologic features not well characterized in literature. The purpose of this study was to describe and characterize the clinical features and imaging findings of CCM.

Materials And Methods: The computed tomography (n = 16) and magnetic resonance (n = 23) images of 23 patients (12 men and 11 women; mean age, 34.6 years) were retrospectively reviewed. All of the patients underwent surgical resection. Follow-up was performed through clinical observations.

Results: Cerebellopontine angle was the most frequently presenting location (n = 10). The tumors were isointense (n = 12) or hypointense but associated with isointense (n = 7) appearance to gray matter on T1-weighted images. However, the tumors seemed to be isointense (n = 6) or isointense and hyperintense (n = 13) on T2-weighted images. On gadolinium-enhanced T1-weighted images, heterogeneous enhancement was seen in 14 lesions. Four lesions had amorphous calcifications, 18 showed peritumoral edema, 14 had cystic areas, 2 had bone hyperostosis, and 8 manifested bone destruction. On initial surgery, 17 patients underwent complete resection, whereas 5 patients underwent subtotal resection of their tumors. The operative result for the remaining patient was unknown. Follow-up was possible in 22 patients. Eleven patients had recurrence and 2 had died.

Conclusions: Clear cell meningioma is a rare subtype of meningioma that occurs in younger patients and often recurs. Cerebellopontine angle is the most affected area in this series. The extent of initial surgical resection is the most important prognostic factor. In radiological studies, CCM tends to have marked heterogeneous enhancement, prominent peritumoral edema, intratumoral cystic components, and involvement of the adjacent bone.