A fast-growing meningioma is probably not benign, according to Mayo Clinic. The overwhelming majority of meningiomas are benign, grow very slowly, usually don't have symptoms and don't require intensive treatment.
Even a benign meningioma can cause problems if it grows large enough, claims Mayo Clinic. Some meningiomas are considered atypical, which means they are neither malignant or benign. If a meningioma has symptoms, they can include blurred or double vision, numbness and weakness, headaches, seizures, changes in personality and problems with speech. The symptoms may be subtle at first.
Meningiomas are usually found at the outer curve and top of the brain, at the base of the brain and in the tissue over the spinal cord, according to the American Brain Tumor Association. Problems occur when the tumor starts to grow downward into the brain or the spinal cord, which places pressure on them. The tumor can also grow upward and cause the bone of the skull to thicken.
Many meningiomas contain cysts, calcifications or tangles of blood vessels, according to ABTA. They are most often found in women and in people 60 years of age or above. Doctors don't know what causes them, but many people with meningiomas have an abnormality on chromosome 22.