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