Difference between revisions of "Peripheral nerve sheath tumours"

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Peripheral nerve sheath tumours (view source)

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==Neurofibroma==
==Neurofibroma==
:This section includes ''plexiform neurofibroma''.
{{Main|Neurofibroma}}
===General===
*May be a part of [[neurofibromatosis]] 1 (NF1).
*A [[painful skin lesion]].
*Composed of Schwann cells, axons, fibrous material.<ref name=pmid17893219/>
 
Classification:<ref name=pmid15486243>{{Cite journal  | last1 = Wilkinson | first1 = LM. | last2 = Manson | first2 = D. | last3 = Smith | first3 = CR. | title = Best cases from the AFIP: plexiform neurofibroma of the bladder. | journal = Radiographics | volume = 24 Suppl 1 | issue =  | pages = S237-42 | month = Oct | year = 2004 | doi = 10.1148/rg.24si035170 | PMID = 15486243 }}</ref>
#Localized - sporatic.
#Diffuse - usually poorly defined, young adults and children; sporatic.
#Plexiform - associated with NF1.
 
===Gross/radiologic===
Gross features (plexiform NF):<ref name=pmid15486243>{{Cite journal  | last1 = Wilkinson | first1 = LM. | last2 = Manson | first2 = D. | last3 = Smith | first3 = CR. | title = Best cases from the AFIP: plexiform neurofibroma of the bladder. | journal = Radiographics | volume = 24 Suppl 1 | issue =  | pages = S237-42 | month = Oct | year = 2004 | doi = 10.1148/rg.24si035170 | PMID = 15486243 }}</ref>
*"Bag of worms" appearance.
 
Radiologic:<ref name=pmid15486243/>
*Fusiform mass.
 
===Microscopic===
Features:
*Spindle cells with wavy nuclei without pleomorphism - '''key feature'''.
**Often described as "shredded carrots".
*May be arranged in fascicles and intermixed with collagen.
**Often no pattern is apparent.
*Moderate increase of cellularity vis-a-vis normal dermis.
*May be poorly or well-circumscribed.
*+/-Plexiform growth pattern - "bag of worms".<ref name=pmid17893219/>
**Multiple well-circumscribed nests.
*Mast cells<ref name=pmid20233971>{{Cite journal  | last1 = Staser | first1 = K. | last2 = Yang | first2 = FC. | last3 = Clapp | first3 = DW. | title = Mast cells and the neurofibroma microenvironment. | journal = Blood | volume = 116 | issue = 2 | pages = 157-64 | month = Jul | year = 2010 | doi = 10.1182/blood-2009-09-242875 | PMID = 20233971 }}</ref> - one has to look for them at high power.
**Very useful for confirming the low power suspicion.
 
DDx:
*[[Plexiform neurofibroma]].
*[[Schwannoma]].
*[[Dermatofibrosarcoma protuberans]] (DFSP) - S-100 -ve.
*[[Ganglioneuroma]].
*Neurotized [[melanocytic nevus]] -  melanocyte nests make the diagnosis, otherwise immunostains are needed to differentiate.<ref name=pmid693815>{{Cite journal  | last1 = Gray | first1 = MH. | last2 = Smoller | first2 = BR. | last3 = McNutt | first3 = NS. | last4 = Hsu | first4 = A. | title = Neurofibromas and neurotized melanocytic nevi are immunohistochemically distinct neoplasms. | journal = Am J Dermatopathol | volume = 12 | issue = 3 | pages = 234-41 | month = Jun | year = 1990 | doi =  | PMID = 1693815 }}</ref>
**Usually have more [[mast cell]]s than neurofibromas.<ref name=pmid8432898>{{Cite journal  | last1 = Carr | first1 = NJ. | last2 = Warren | first2 = AY. | title = Mast cell numbers in melanocytic naevi and cutaneous neurofibromas. | journal = J Clin Pathol | volume = 46 | issue = 1 | pages = 86-7 | month = Jan | year = 1993 | doi =  | PMID = 8432898 }}</ref>
 
====Images====
<gallery>
Image:Neurofibroma_(1).jpg | Neurofibroma - low mag. (WC)
Image:Neurofibroma_(2).jpg | Neurofibroma - intermed. mag. (WC)
Image:Neurofibroma_(3).jpg | Neurofibroma - high mag. (WC)
</gallery>
www:
*[http://radiographics.rsna.org/content/24/suppl_1/S237/F9.expansion.html Plexiform neurofibroma (rsna.org)].
*[http://radiographics.rsna.org/content/24/suppl_1/S237/F10.expansion.html Plexiform neurofibroma (rsna.org)].
*[http://path.upmc.edu/cases/case304/micro.html Plexiform neurofibroma - several images (upmc.edu)].
*[http://eyewiki.aao.org/File:Orbital_Neurofibroma_-_S100.JPG Neurofibroma - S-100 (eyewiki.aao.org)].
 
===IHC===
Features:<ref name=pmid12692193>{{cite journal |author=Hirose T, Tani T, Shimada T, Ishizawa K, Shimada S, Sano T |title=Immunohistochemical demonstration of EMA/Glut1-positive perineurial cells and CD34-positive fibroblastic cells in peripheral nerve sheath tumors |journal=Mod. Pathol. |volume=16 |issue=4 |pages=293–8 |year=2003 |month=April |pmid=12692193 |doi=10.1097/01.MP.0000062654.83617.B7 |url=http://www.nature.com/modpathol/journal/v16/n4/full/3880761a.html }}</ref>
*S100 +ve -- wavy pattern.<ref name=pmid22742554>{{Cite journal  | last1 = Chen | first1 = Y. | last2 = Klonowski | first2 = PW. | last3 = Lind | first3 = AC. | last4 = Lu | first4 = D. | title = Differentiating neurotized melanocytic nevi from neurofibromas using Melan-A (MART-1) immunohistochemical stain. | journal = Arch Pathol Lab Med | volume = 136 | issue = 7 | pages = 810-5 | month = Jul | year = 2012 | doi = 10.5858/arpa.2011-0335-OA | PMID = 22742554 }}
</ref>
*CD34 +ve.
*Glut1 +ve.
*EMA +ve/-ve.
*NF +ve/-ve.<ref name=pmid22742554/>
*MART-1 -ve.<ref name=pmid22742554/>
**Positive in neurotized melanocytic nevi.
 
===Sign out===
<pre>
FOURTH TOE, LEFT, EXCISION:
- NEUROFIBROMA.
</pre>
 
====Micro====
The sections show skin with a lesion composed of irregular-shaped groups of bland dermal spindle cells with wavy nuclei and pale-eosinophilic cytoplasm. Mast cells are seen scattered throughout the lesion. Thick collagen separates the clusters of the spindle
cells. There is no nuclear atypia. Mitotic activity is not appreciated. No melanocytic nests are identified.
 
The overlying epidermis matures to the surface.
 
=====Alternate=====
The sections show skin with an unencapsulated dermal spindle cell lesion with navy nuclei that have a likeness to shredded carrots. Occasional mast cells are present within the lesion. There is no nuclear atypia. Mitotic activity is not appreciated. No melanocytic nests are identified.


==Neurothekeoma==
==Neurothekeoma==
Michael
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