+ General Considerations

  • Types: neuronoma, neurolemmoma, Schwannoma, malignant Schwannoma, neurofibroma, and neurofibrosarcoma
  • Peripheral nerve sheath tumor is preferred Schwann cells are origin and all have similar biologic behaviour
  • Fibrous, osteoid, chondroid, myxoid, and squamous patterns may be observed due to tumor differentiation
  • Peripheral nerve sheath tumor commonly involve nerve roots of the brachial plexus
  • Tumor progression occurs proximally and distally and may involve the spinal cord
  • Metastatic disease is rare although pulmonary metastasis has been reported

+ Peripheral Nerve Sheath Tumor Classification

  • Peripheral nerve sheath tumor classified according to level of involvement as:
  • Peripheral: tumor involvement distal to brachial or lumbrosacral plexus
  • Plexus: tumor involvement of nerves in brachial or lumbrosacral plexus and spinal nerves distal to intervertebral foramina
  • Root: tumor involvement of ventral or dorsal nerve roots or tumor entering intervertebral foramina

+ Clinical Features

  • Clinical signs are slowly progressive
  • Lameness (77%) and muscle atrophy (93%) are common with pain and palpable mass other findings

+ Diagnosis

  • Clinical signs and physical examination
  • Advanced imaging using CT and MRI provides an indication of level of involvement and associated changes
  • Myelography recommended for suspected spinal nerve root involvement
  • EMG useful in delineating nerve root involvement
  • CSF rarely useful

+ Treatment

Surgical treatment is recommended with technique depending on location:

  • Local resection
  • Amputation
  • Laminectomy
  • Combination of these procedures

+ Prognosis

  • Prognosis depends on level of involvement and ability for complete surgical resection
  • Excellent prognosis for peripheral classification of peripheral nerve sheath tumors due to ability for complete resection with no death related to tumor
  • Poor prognosis for plexus and root peripheral nerve sheath tumors with death due to tumor in 78%
  • No significant differences between plexus and root groups although trend for plexus tumors to survive longer