Intracranial clear cell meningioma: Clinical study with long-term follow-up in 24 patients

•One of largest series (n = 24) on intracranial clear cell meningiomas (CCMs).•Intracranial CCMs had a predilection to affect younger patients.•A cutoff point of 3% MIB-1 index is a valuable prognostic indicator in CCMs patients.•Radiotherapy should be recommended to patients underwent STR or with MIB-1 index ≥3%.•First study elucidating the management of a pregnant woman who has a remnant CCM. Clear cell meningioma (CCM) is a rare disease, and controversy about treatment and prognosis of CCMs still exists. We aimed to clarify the natural history, radiological features, histological characteristics, management and prognosis of intracranial CCMs. We performed a retrospective study of 24 patients with intracranial CCM who were treated at West China Hospital from January 2006 to January 2018. The clinical features, radiologic findings, diagnosis, treatment, and outcome of these patients were analyzed retrospectively. Additionally, a literature review of intracranial CCMs was performed. Among 3554 surgeries for intracranial meningiomas, we identified 24 (0.7%) cases of CCMs. The most common localization was the frontal lobe (n = 9, 37.5%). The mean age at diagnosis of CCMs was significantly younger than that of total meningiomas patients (46.7 ± 15.8 versus 55.4 ± 14.8 years). They had a high rate (54.2%) of atypical radiological manifestations, such as cystic component, heterogeneous enhancement, and irregular shape. During the average follow-up of 61.1 months, four patients (19.0%) suffered from tumor recurrence. Kaplan-Meier analysis showed that patients with subtotal resection (STR) or a MIB-1 index ≥3% had significantly shorter progression-free survival (PFS) compared to gross total resection (GTR) and MIB-1 index