Meningiomas grow on the surface of the brain (or spinal cord), and therefore push the brain away rather than growing from within it. Most are considered “benign” because they are slow-growing with low potential to spread.
Link to.. What is a Meningioma?. tag Meningioma tumors can become quite large. Diameters of 2 inches (5 cm.) are not uncommon. Meningiomas that grow quickly and exhibit cancer-like behavior are called atypical meningiomas or anaplastic meningiomas, and are fortunately rare. Meningiomas represent about 20 percent of all tumors originating in the head and 10 percent of tumors of the spine.
About 6,500 people are diagnosed with meningiomas each year in the United States. This type of tumor occurs more frequently in people with a hereditary disorder called neurofibromatosis type 2 (NF-2).