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SOLITARY NEUROFIBROMA: IMAGE
LINKS1
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(ESCOP)
Solitary neurofibroma is a
localized neurofibroma which is usually not associated with
neurofibromatosis.
Age:
This lesion usually occurs between the ages of 20 and 30.
Clinical presentation:
Solitary neurofibromas are papular, nodular or pedunculated lesions and
greyish white in colour. These painless , slow growing tumours are soft
in consistency. Usually there is no evidence of secondary degenerative
changes.
(D/D:
Schwannoma).
The tumour appears to originate within the endoneurium.
Microscopic features:
The lesion is
nonencapsulated ( schwannoma is well encapsulated) and circumscribed.
A grenz zone separates the lesion from the epidermis. The tumour is
composed of interlacing bundles of elongated cells with wavy nuclei.
Several small nerve fibres are also present. The tumour cells are set in a
fibromyxoid backround. Mast cells are present. Sometimes degenerative
nuclear pleomorphism may be present (bizarre or atypical neurofibroma).
Note: Presence of mitotic activity in neurofibroma is indicative of
malignancy. (Mitosis is common in schwannoma).
Variants:
-Cutaneous Lipomatous
Neurofibroma: Read abstracts
-Myxoid neurofibroma - Myxoid Tumours of Soft Tissue:
Abundant mucin is
present in the matrix (S100 necessary to distinguish from
intramuscular myxoma.)
D/D:
Myxoid DFSP
-Collagenous
neurofibroma - Thick
collagen bundles are present in the matrix.
-Epithelioid
neurofibroma - The
tumour cells are rounded with eosinophilic cytoplasm.
Read abstract
-Granular neurofibroma
- The cells contain
granular PAS positive, diastase resistant cytoplasm.
-Pigmented
neurofibroma
- Scattered tumour cells
contain melanin pigment (S100 protein, HMB45 and Melan A positive)
-Dendritic Cell
Neurofibroma With Pseudorosettes:Read abstract
Immunohistochemistry:
There is proliferation of all the elements of the peripheral nerve -
Schwann cells, axons , perineural cells (plexiform type) and fibroblasts.
Hence 30- 40% tumour cells are positive to S100 protein (in neurilemmoma
100% cells are positive). Axons are neurofilament positive. Factor XIIa
positive and CD34 positive cells are also sometimes present.
NEUROFIBROMATOSIS: click
here
DIFFUSE NEUROFIBROMA:
IMAGE LINKS1
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3
4
5 (ESCOP)
Age:
Occurs between ages of
10-30 years.
Site:
Head and neck area.
Clinical presentation:
Plaque like elevation
of the skin. On cut section, entire subcutis is thickened by firm greyish
tissue.
Microscopic features :
Poorly defined
lesion with diffuse replacement of the dermis and subcutis by
neurofibromatous tissue. It diffusely infiltrate subcutaneous fat. It
does not destroy but envelops the normal structure. The matrix of the
lesion is uniform consisting of fine fibrillary collagen. The Schwann
cells have shorter and more rounded contour in diffuse neurofibroma.
Clusters of Meissner bodies may be present. Occasionally multinucleate
giant cells may be present.
Differential diagnosis:
Dermatofibrosarcoma
protruberance -
More storiform pattern and CD34 positive and S100 protein negative.
PLEXIFORM NEUROFIBROMA:
IMAGE LINK
(Dr. Weems)
IMAGE LINKS1
2
3
4
(ESCOP)
Age:
Usually occurs in children and young adults.
Site:
Head and neck region
Clinical presentation:
The expanded nerves form irregular, convoluted cords and nodules.
GROSS:
CLICK
HERE(DermAtlas)
Plexiform neurofibroma is associated with hyperpigmented skin, thickening
of soft tissue and hypertrophy of bone.
Microscopic features:
Nodules of tortuous, expanded nerve branches cut in various planes of
section.
There is prominent
myxoid change. In some cases cells spill out from the nerve into the soft
tissue.
In early stage, the affected nerve displays increase in endoneurial
matrix. In the late stage the nerve fibres are replaced by proliferation
of Schwann cells together with thick wavy collagen bundles
Presence of mitotic figures is indicative of malignancy.
Immunohistochemistry:
Axon- Neurofilament positive
Schwann cells- S100 protein positive
Perineurial cells- EMA positive
D/D:
Plexiform Schwannoma
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IMAGE LINKS
(Dr Weems):
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