Introduction: Atypical meningiomas (WHO grade II) are known to recur in up to 30% of cases. While the mean time to progression is 24 months a number of tumour progress early. The factors predicting early progression are currently not described. We aim to investigate the imaging and pathological factors that predict early aggressive behaviour of atypical meningioma and its relation to outcome.
Methods: Triple centre, retrospective study. All adults with WHO grade II meningioma (2007 WHO classification) diagnosed between 2007 and 2012. MRI characteristic (tumour location, oedema, bone erosion, extent of resection) as well as pathology characteristics (nuclear atypia, mitotic index, brain invasion, and necrosis, MIB-1 labelling) were assessed. Extent of resection was defined as gross total resection (GTR: Simpson I-III) or subtotal resection (STR: Simpson IV-V). Recurrence was classified into early and late (<2 years vs. >2 years). The modified Rankin score (mRS) was used to assess functional outcome at last follow up.
Results: 220 cases were identified with median age 61. 70 patients had recurrence, of which 18, 39 and 29 recurred within 1 year, 2 years and > 2 years following surgery respectively. Independent factors associated with early (within 2 years) recurrence include parafalcine location (p=0.009), edema on scan (p=0.033), atypia (p=0.04) and the presence of residual meningioma (p=0.029). Early recurrence was related to mRS at last follow up (p=0.09).
Conclusions: Atypical meningioma exhibit heterogeneous behaviour patterns. Independent factors associated with early aggressive behaviour include parafalcine location, edema, atypia on histology, and subtotal resection. Early recurrence of atypical meningioma was significantly associated with mRS at last follow-up. More work should be done to identify the cohort of patients at risk of early recurrence within the group of atypical meningioma.
Patient Care: Identifying patients at risk of early recurrence of atypical meningioma may help direct aggressive adjuvant treatment and improve outcomes.
Learning Objectives: Atypical meningioma constitute a heterogeneous group of patients with different clinical courses.
Factors related to early recurrence as well as recurrence in general are identified and discussed.