+ General Considerations

  • Synonyms: neurogenic sarcoma, neurofibrosarcoma, malignant Schwannoma, malignant neurolemmoma, and hemangiopericytoma
  • Hemangiopericytoma may not exist as blood vessel pericyte origin has not been demonstrated and they have same histologic features as a peripheral nerve sheath tumor and stain positive with S-100 immunohistochemistry
  • Female predisposition for hemangiopericytoma
  • Sites: distal extremities are common
  • 3 groups of peripheral nerve sheath tumors:
  • Peripheral (i.e., nerves away from the brain and spinal cord)
  • Nerve root (i.e., nerves immediately adjacent to brain and spinal cord)
  • Plexus (i.e., brachial or lumbrosacral)
  • Peripheral form is more amenable to treatment than either the plexus or root forms
  • Gross appearance: nodular, lobulated, or poorly defined without histologic encapsulation despite appearing encapsulated and discrete clinically
  • Primary cutaneous neurofibroma is rare
  • Solitary (common) or multiple (tortuous and nodular enlargement of nerve = neurofibromatosis)
  • Adherence to deeper tissues and infiltration of underlying fascia, muscle, and skin is common
  • Axial peripheral nerve sheath tumors can cause nodular enlargement and compress adjacent nerves causing unilateral lameness, muscle atrophy, paralysis, and pain with spinal cord invasion possible in up to 50% if grade III STS
  • Metastatic rate: 10%-20% for grade I and 50% for grade III
  • Peripheral nerve sheath tumor site:
  • Nerve root: 72% local tumor recurrence rate with a median DFI 7.5 months and MST 12 months
  • Plexus: 72% local tumor recurrence rate with a median DFI 1 month and MST 5 month

See Soft Tissue Sarcoma for more information