To analyse whether the WHO grade of intracranial meningiomas differs itself depending on patients and meningioma characteristics at diagnosis.

Single center retrospective study of a series of consecutive patients with primary intracranial meningiomas who underwent surgery between January 2007 and March 2014. Patients (age, sex, outcome) and meningioma characteristics (histological diagnosis, tumor location, WHO grading, size, extend of peritumoral edema and tumor recurrence rate) were analysed.

Of 240 included patients, 184 (76.7%) were female and 56 (23.3%) were male. 17 patients (7.1%) were in age group 20-40 years, 112 (46.7%) in group 41-60 years and 111 (46.3%) were in age group > 60 years. 189 patients (78.8%) were diagnosed with WHO grade I, 49 (20.4%) WHO grade II and 2 (0.8%) had a WHO grade III meningioma. WHO grade II meningiomas were significantly more frequent in the age group 20-40 years compared to age group 41-60 years (chi-square p < 0.05). Convexity meningiomas were significantly more frequent classified as WHO grade II meningiomas compared to all other locations (chi-square, p < 0.01). Mean calculated tumor volume and the tumor volume determined by volumetric measurement was significantly larger in grade II meningioma patients compared to grade I (46.3 ± 40.5 cc grade II versus 21.8 ± 27.8 cc grade I and 45.3 ± 38.2 cc versus 23.1 ± 30.0 cc respectively; t test < 0.01). Extend of the peritumoral edema was significantly larger in patients with grade II meningiomas (Wilcoxon test, p < 0.05). Short term outcome did not differ between different age groups nor was it associated with tumor size. During a mean follow up of 49 months (min 3, max 144 months) recurrence rate was significantly higher in WHO grade II (4 out of 49 [8.2]%) compared to WHO grade I patients (3 out if 186, [1.6%]; Chi-square, p < 0.05).

In this series atypical meningioma was associated with younger age, location on the convexity, larger tumor size and more peritumoral edema.