Clear Cell Meningioma: A Clinicopathologic Study of a Rare Meningioma Subtype in 35 Patients.

Objective: Clear cell meningioma (CCM) is a rare histologic variant, accounting for only 0.2%-0.8% of all meningiomas. Given their relative infrequency, few cases have been reported. We have presented one of the largest series of patients with intracranial CCM and reported the treatments and outcomes of these patients.
Methods: Patients with histologically proven CCM from 2003 to 2018 were identified for inclusion in the present study. Relevant clinical and radiographic data were obtained via retrospective review and analyzed. Kaplan-Meier and Cox proportional hazards analyses were used to compare overall and progression-free survival.
Results: A total of 35 patients had undergone surgical resection for CCM, including 18 women and 17 men, with a mean age of 59.3 years. Gross total resection was achieved in 22 patients (62.9%), and 11 patients (31.4%) had received adjuvant postoperative radiotherapy. Tumors recurred in 17 patients (48.6%), with a mean time to recurrence of 31.3 months. The mean postoperative follow-up was 66.3 months. On multivariable analysis, adjuvant radiotherapy and gross total tumor resection were both independently associated with prolonged progression-free survival (P < 0.033), although not with overall survival (P >0.274).
Conclusions: The data from the present series of 35 patients with CCM have shown distinct contrasts to previous series, with an older mean age and a nearly 1:1 male/female ratio. Although gross total resection and adjuvant postoperative radiotherapy were both independently associated with longer progression-free survival for patients with CCM, tumor recurrence has remained a challenge in the treatment of these patients.
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