Schwannoma

Synonyms:

Vestibular Schwannoma a.k.a. acoustic neuroma (formerly neurilemmoma)

Diagnosis:

Suggested by MRI and confirmed by pathology (brain biopsy/resection)

Pathology:

Histology:

  • Antoni A pattern: cellular, Spindle cells. Verocay bodies (palisading).
  • Antoni B pattern: less cellular, round nuclei, vacuolated cells, microcysts

Immunohistochemsitry: Positive S100

Findings on Investigations:

MRI:

  • VIII nerve. Extends into the internal auditory canal IAC. May affect cranial nerves VII, V or any other. Cisternal & intracanalicular portions. Cysts may occur. No calcifications, no bony reaction, no dural tail.
  • May occur in spinal nerve roots. Hourglass/Dumbbell shaped mass through the intervetrebal foramen
  • T1 MRI with gadolinium: isointense to hypointense. Enhancement
  • T2: variable signal intensity
  • Fat saturated MRI: distinguishes fat.
  • Associated with arachnoid cyst

Audiological testing: may be impaired
Consider:

  • BAER
  • Electronystagmography ENG

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