- Benign peripheral nerve sheath tumor arising from Schwann cells of cranial nerve (CN) VIII (vestibular portion) within the cerebellopontine angle-internal auditory canal (CPA-IAC)
- WHO grade 1
- Originates from Schwann cells surrounding CN VIII vestibular segment
- CN VIII inferior vestibular branch > superior branch
- CN V and CN VII schwannomas not uncommon
- Origin in CN VIII cochlear portion is rare
- Bilateral vestibular schwannoma hallmark of neurofibromatosis type 2 (NF2)
- Mutations in NF2 tumor suppressor gene in majority of sporadic and familial cases
- Associated abnormality: arachnoid cyst or “CSF cap” (7%–10% of cases)
- Variable hypercellular (Antoni A) and more hypocellular (Antoni B) areas are characteristic microscopic features
- ±Intratumoral cysts, microhemorrhage
- Most common during adulthood (age 40–60 years)
- Uncommon in children unless associated with NF2
- Majority of cases exhibit slow growth over time
- Common presenting signs/symptoms: unilateral sensorineural hearing loss
- Treatment: surgical resection
- Prognosis: size >2 cm and involvement of IAC fundus and/or cochlear aperture are negative prognosticators for hearing preservation
- Well-marginated, enhancing mass within the CPA or CPA-IAC with “ice cream on cone” morphology
- Expansion of the IAC (in contrast to meningiomas)
- Small lesions can be entirely intracanalicular
- Calcification, cystic degeneration might be seen; hemorrhage rare
- Small lesions could be entirely intracanalicular and nonvisible on CT imaging
- Enhancement on contrast-enhanced CT imaging
- T1WI: usually hypointense to isointense
- T2WI: high-resolution sequences (SPACE, CISS, or FIESTA) optimize visualization; appears as a hypo- to isointense CPA-IAC filling defect (ovoid if small, “ice cream on cone” if larger); ± hyperintense tumoral cysts
- T2*GRE: ±signal blooming from foci of microhemorrhage
- T1WI+C: avid enhancement
- MRI without and with intravenous contrast, including high-resolution T2-weighted sequences through the CPA-IAC (SPACE, CISS, or FIESTA); serial MRI for small lesions to ensure stability
For more information, please see the corresponding chapter in Radiopaedia.
Contributors: Rachel Seltman, MD, and Jacob A. Eitel, MD
Furuta S, Takahashi S, Higano S, et al. Prediction of the origin of intracanalicular neoplasms with high-resolution MR imaging. Neuroradiology 2005;47:657–663. doi.org/10.1007/s00234-005-1400-x.
Osborn AG, Salzman KL, Jhaveri MD. Diagnostic Imaging (3rd ed). Elsevier, Philadelphia, PA; 2016.
Thamburaj K, Radhakrishnan VV, Thomas B, et al. Intratumoral microhemorrhages on T2*-weighted gradient-echo imaging helps differentiate vestibular schwannoma from meningioma. AJNR Am J Neuroradiol 2008;29:552–557. doi.org/10.3174/ajnr.A0887.
Woodruff JM, Kourea HP, Louis DN, et al. Schwannoma. In Kleihues P, Cavenee WK (eds), Tumours of the Nervous System. IARC Press, Lyon, France; 2000:164–166.
Zealley IA, Cooper RC, Clifford KM, et al. MRI screening for acoustic neuroma: a comparison of fast spin echo and contrast enhanced imaging in 1233 patients. Br J Radiol 2000;73:242–247. doi.org/10.1259/bjr.73.867.10817038.
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