Epidemiology

• Commonly located within the internal acoustic canal and can extend into the cerebellopontine angle (most common tumor of the cerebellopontine angle)

Etiology

Pathophysiology

Clinical features

• Early symptoms: as a result of tumor expansion into the internal acoustic canal (internal auditory meatus), causing pressure on the vestibulocochlear nerve (CN VIII)
  • Cochlear nerve involvement
    • Unilateral sensorineural hearing loss (most common symptom)
    • Tinnitus
  • Vestibular nerve involvement
    • Dizziness
• Late symptoms: caused by pressure of adjacent structures within the cerebellopontine angle
  • Trigeminal nerve (CN V) involvement: paresthesia (numbness), hypoesthesia (decreased sensation), and/or unilateral facial pain
  • Facial nerve (CN VII) involvement: peripheral, unilateral facial weakness that can progress to paralysis
  • Compression of structures in posterior fossa

Diagnostics

Pathology

• Spindle cells (fibroblasts) in palisades (Antoni A tissue) alternating with myxoid hypocellular areas (Antoni B tissue)
  • A characteristic finding of neuromas is the simultaneous occurrence of areas with densely packed nuclei (palisade pattern; A) and scattered or anuclear areas (B). There is also a large number of vacuolated cells (C).
• S-100 positive
  • S-100 can be seen in melanoma, schwannoma, Langerhans cell histiocytosis

Treatment