My husband had an MRI March 12 and we were told he had what was probably a glioma. We were told to be as aggressive as possible and he had surgery to remove it two weeks later. He was diagnosed with a Grade II Oligoastrocytoma. We are going in for his first follow up MRI in July and then every 3 months. I would at least get a second opinion and do what feels right to you. We were not comfortable waiting and watching because some gliomas can be very aggressive and without a biopsy it is impossible to know what you are dealing with. That is why we went the route that we did.
The only “symptom” that my husband had was a possible seizure at work. Nobody saw what happened. He was found unconscious by coworkers and rushed to the ER thinking he had fallen and hit his head or something.