Clinical History:

A 39-year-old woman has noted persistent headaches and dizziness for the past 4 months. She also notes diminished hearing on the left. Audiometry reveals the findings shown here:

The audiogram shows marked diminution in hearing on the left, worse at higher ranges, consistent with a sensorineural hearing loss. The impairment will be present and as bad for both air and bone conduction.

MR imaging is performed, followed by surgery.

Radiology and Microscopic Pathology:

The appearance of the lesion with MR imaging indicates that the mass is circumscribed and impinges upon the cerebellum. Histologically, the tumor is composed of spindle cells with abundant pink cytoplasm and bland oblong nuclei. (images 2.1 to 2.3).

Questions:

1. Where is this mass located?

This mass is located at the cerebellopontine angle. This is the anatomic location for the eighth cranial nerve (acoustic nerve).

2. What is the diagnosis?

Acoustic neuroma (schwannoma). This is a lesion whose cell of origin is the schwann cell which forms the myelin sheath around nerve fibers.

3. What is the prognosis?

Good. These lesions are benign and can be excised.

4. Name a condition in which this lesion can be seen in association with multiple neoplasms.

Neurofibromatosis is an autosomal dominant condition in which cafe-au-lait spots can appear on the skin. Neurofibromatosis type 2 is marked by bilateral acoustic neuromas.