That's why AN is a misnomer and the accurate terminology is "vestibular schwannoma".
This seems as good a time as any to quibble about this.
The VIII nerve is the vestibulocochlear nerve, and can quite correctly be called the acoustic nerve (or auditory nerve). It splits into two branches, the vestibular branch for balance, and the cochlear branch for hearing.
The term neuroma is a general term for a nerve tumor; a schwannoma is a specific kind of neuroma, arising from the schwann cells that encase some cranial nerves, including the VIII nerve.
Both vestibular schwannomas and cochlear schwannomas have been reported, although the vestibular schwannoma is more common. Both kinds can rightly be called acoustic schwannomas, as they are schwann cell tumors of the acoustic nerve. And both can rightly be called acoustic neuromas, as they are both tumors of the acoustic nerve.
While it is appropriate for a radiologist reading an MRI to identify the tumor type and origin as specifically as possible, it is perfectly acceptable to use the less specific term as well. They are in fact acoustic neuromas.
Ok, I'll stop now.
Steve