dr james c wittig, orthopedic oncologist, new york, new jersey
Patient Education
Neurofibroma

GENERAL INFORMATION

A neurofibroma is a  benign tumor of the peripheral nerves, also known as solitary neurofibroma. Neurofibromas can arise as solitary entities or as part of a syndrome, namely neurofibromatosis. Neurofibromatosis is a genetic disease where patients develop multiple peripheral nerve tumors (neurofibromas and schwannomas) as well as cutaneous manifestations. A neurofibroma is not related to fibromatosis which is an entirely different entity

CLINICAL DATA

Benign peripheral nerve tumor 
May be a single lesion
Develops during childhood
Close to 5% can transform to MPNST usually only in setting of neurofibromatosis
As an isolated tumor (not in setting of neurofibromatosis) 
o Non-familial incidence
o Little malignant change
o Little recurrence
o More common
These are superficial tumors of the dermis: 
o Orbit
o Face
o Neck
o Back
o Inguinal area

DIFFERENTIAL DIAGNOSIS

MPNST
Schwannoma (neurileoma)
Neurofibroma

CLINICAL PRESENTATION

Sign/Symptoms

Slow-growing and usually small
Painless nodule

Prevalence

No predilection for sex or race
Somewhat rare
Usually between 20 and 30 years
Other age could be affected as well

Site

Distributed throughout body surface

RADIOGRAPHIC PRESENTATION

X ray

o May reveal soft tissue mass
o Displacement of neurovascular bundle may also be apparent

CT

o Fusiform shape
o Nerve can often be seen entering/exiting the mass
o Perilesional rim

MRI

o Tubular structure
o Discrete margins, but sometime noticeable low signal intensity rim 
o Attenuation lower than the muscle
o Signal intensity similar to or higher than skeletal muscle in T1W
o High signal intensity in T2W

 



Fig. 1 Axial MRI of a large neurofibroma of lower extremity 

PATHOLOGY

Gross

Gray-white
 • Deep tumors are often large
Can resemble a “bag of worms” refrred to as a plexiform neurofibroma
Lack secondary degenerative changes o Found in schwannomas
If found in major nerves
o Expand structures in fusiform manner
o Normal nerve can be seen entering/exiting
o If contained by epineurium--->Possesses true capsule
o Usually appear circumscribed but are nonecapsulated



Fig. 2 Gross photograph of gray-white ovoid specimen after resection

Microscopic

Interlacing bundles of cells
o Elongated cells
Wavy, dark-staining nuclei
Intimately associated with collagen
Small to moderate amounts of mucoid separate cells and collagen
o Stroma of tumor dotted with occasional
Mast cells
Lymphocytes
Sometimes xanthoma cells
May be more cellular
o With schwann cells, but no biphasic pattern
o Uniform collagen matrix devoid of mucosubstances
o Cells arranged in fascicles, whorls, or storiform pattern
o May contain Antoni A areas
o Not encapsulated so can be distinguished from schwannoma
o Involves the nerve fascicles; does not arise at periphery like a schwannoma and displace the fascicles



Fig. 3  Low power magnification shows  wavy elongated schwann cells resembling nerve tissue

IMMUNOHISTOCHEMISTRY

Positive for: 
o S100 (scattered)
o EMA

PROGNOSIS

BIOLOGICAL BEHAVIOR

Usually arises in small nerves in the skin
Readily extend into soft tissue
Rarely see malignant change with isolated neurofibromas
Low recurrence rate after surgery (even complete resection)
No metastasis

TREATMENT

Simple excision, usually adequate
Radiotherapy:
o May be considered, but  not usually necessary


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