ATYPICAL AND MALIGNANT MENINGIOMAS - IMPORTANCE OF MICRONECROSIS AS APROGNOSTIC INDICATOR

Twenty-eight patients with a diagnosis of either atypical or malignant meningioma, according to the World Health Organisation (WHO) classifi cation, were followed up to relate histopathological features with tim es to recurrence and death. Five year disease-free survival was 41% wi th a median disease free survival of 2 7 months. Micronecrosis was the only histopathological feature associated with increased risk of recu rrence (rate ratio, 3.73; 95% confidence interval 1.03-13.6). At 36 mo nths, 32% of patients with micronecrosis were alive compared with 71% of patients without micronecrosis. Brain invasion was not associated w ith disease-free survival. After recurrence, median survival was 7 mon ths and was not correlated with any histopathological feature. The pre valence of micronecrosis was estimated from random samples of benign, atypical and malignant meningiomas to be 8%, 42% and 71% respectively. The relevance of these findings and the current WHO classification is discussed.