Hi My Son Is 26 Years Old. His Current MRI

Hi my son is 26 years old. His current MRI revealed a diffuse abnormal signal intensity within the right mastoid air cells. When he was around 7 years of age he had a bad infection and when they did a ct scan it reviewed an oppacification that they never new what it was and doctors advised not to be concerned only if symptoms arose. what do you think we should do now. I am really concerned and would really appreciate your help.