Hello alkitsa and welcome to NeuroTalk.

A lesion is something found on MRI which should not be there. What causes anomalies on MRI? Many things. Since your Dr. is uncertain of the cause he may just need to follow you to see if anything thing else shows up symptom wise or in testing.

A MRI report is more helpful as there is an "impression" section that will give you an idea of possible causes to anomalies found on MRI. However, those possible other causes need to be determined by your Dr. based on medical history, other testing, ect.

For now try and relax and be thankful your current MRIs are clear and you are not having seizures