I Have Been Treated With Malignant Melanoma, Stage III. On

I have been treated with malignant melanoma, stage III. On my last two brain MRI's what looks like a meningioma has appeared. I had a normal MRI in November of 2012, but in late 2013, the brain lesion appeared. My PET scans do not indicate that this lesion/meningioma is showing sign of being cancerous. This tumor is in my left parasagital/parietal area of my brain. Could this be melanoma mimicing a meningioma? I read that this is a possiblity. I am having some vague symptoms and I am concerned that something serious could be misdiagnosed and not treated.