A meningioma is a type of tumor that arises from the meninges, which are the protective membranes that surround the brain and spinal cord. It is typically a slow-growing, usually benign tumor, derived from the cells of the arachnoid cap cells or the meningeal cells themselves. Meningiomas are the most common primary brain tumor. Fortunately, most are benign and slow-growing although up to 10% can grow rapidly. They are more common in women than men and can occur in all ages but are typically seen in middle-aged and older adults. Most meningiomas needing surgery can be removed through one of several minimally invasive keyhole approaches.