Meningiomas are tumours that arise from the coverings of the brain. Often regarded as ‘benign’, meningiomas can compress important parts of the brain - causing permanent disability (e.g. blindness) or death through uncontrolled growth. Predicting tumour recurrence is difficult. This study will use previously collected samples of meningioma from between 2002 and 2010 to examine whether the immune reaction that occurs within meningiomas is useful in predicting which tumours may recur early. The study also hopes to gain insights into how the immune cells interact with the meningioma and whether new immune-modifying drugs may be useful in treatment. The study will be carried out at Auckland City Hospital and the University of Auckland.