Nerve Sheath Tumors
- Schwannoma – 7% intracranial, 5% multiple
(NF2)
- Nerve
pushed aside
- M=F,
younger if NF2
- From
neural crest cells
- Arise
from entry zone of sensory nerves, flexor surface extremities
- Can be
intraaxial
- Account for
30% of spinal tumors
- Fusiform
when intraneural, enlarge and become eccentric
- Antoni A
– fusiform with reticulin and collagen; contains verocay bodies (anuclear
material with pallisading cells)
- Central
schwannomas have increased A regions
- Antoni B
– stellate round cells in stroma, school of fish pattern
- angiomatoid
vascular collections (thick-walled vessels)
- Verocay
bodies (cells aligned around a region) in Antoni A regions
- Contains
cyst, hemorrhage, mitosis (no change in prognosis)
- Acoustic
schwannoma
- Arise
from vestibular portion (usually superior) of VIIIth cranial nerve
- Presentation:
Tinnitus, slowly progressive hearing loss, gait instability, cerebellar
dysfunction
- Associated
with neurofibromatosis
- Radiology:
Homogenously enhancing CP angle mass with erosion of internal auditory
canal
- Treatment:
Surgical excision
- Prognosis:
Many long-term survivors
- Neurofibroma
- Nerve included
in tumor
- Not
intracranial
- Consist
of schwann cells, fibroblasts, collagen, reticulin
- Fusiform,
unencapsulated, infiltrate nerves
- Wavy
axons run through loose matrix
- No fat
or hemorrhage (unlike schwannomas)
- Often
dumbbell-shaped
- Can
undergo malignant change
- Most are
solitary cutaneous nodules on small terminal nerves
- Plexiform
– very large; if proximal, nearly always associated with NF1
- Perineuroma – rare, adolescent, distal
extremity
- EMA+,
S100-
- Motor
neuropathy
- Onion
ball perineural cells
- Malignant
peripheral nerve sheath tumor
- Very
painful
- Increased
cellularity, mitosis, necrosis
- 50% have
NF1
- rarely
from schwannoma
- worse
prognosis if necrosis, large, or associated with neurofibroma