Spinal Clear Cell Meningiomas: Clinical Features and Factors Predicting Recurrence.

OBJECTIVE: As a World Health Organization grade II tumor of the nervous system, clear cell meningioma (CCM) is an uncommon histologic variant of meningioma. Spinal CCMs are even rarer, with <100 spinal CCMs reported in the English literature. We present this study to characterize clinical manifestations of spinal CCMs and determine the factors predicting recurrence. METHODS: A literature search was performed for relevant case reports and series in PubMed and Embase until September 1, 2019. These articles were reviewed to identify clinical features, treatment modalities, and prognosis of patients with spinal CCMs. RESULTS: Eighty-four spinal CCMs were analyzed. Of these patients, 36 (42.9%) were young (age <= 18 years), and the mean age at resection was 24 years. Fifty-three patients (63.1%) were female and 31 (36.9%) were male. Most of the tumors (56/84, 66.7%) were located in the lumbar region. In 31 patients (36.9%) >2 segments in the craniocaudal direction were involved (number of involved segments >= 3 levels). Gross tumor resection was performed in 77 patients (91.7%). Twenty patients (23.8%) showed radiographic evidence of recurrence during follow-up. Recurrence-free survival at 1, 5, and 10 years after resection of spinal CCM was 87%, 71%, and 47%, respectively. Multivariate analysis showed that age <= 18 years (hazard ratio [HR], 3.64; P = 0.024), subtotal resection (HR, 3.43; P = 0.031), and segments involving >= 3 levels (HR, 5.66; P = 0.002) were associated with increased recurrence. CONCLUSIONS: Spinal CCMs have their own unique clinical features compared with conventional spinal meningiomas and intracranial CCMs. Spinal CCMs have a predilection to affect younger patients, are prone to appear in the lumbar region, and have a high recurrence rate. Age <= 18 years, subtotal resection, and involvement of long segments (>= 3 levels) are positive predictors of recurrence.