Difference between revisions of "Peripheral nerve sheath tumours"

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'''Peripheral nerve sheath tumours''', abbreviated '''PNSTs''', are common in [[neuropathology]] and occasionally show-up elsewhere.  A very common PNST is the [[Peripheral nerve sheath tumours#Schwannoma|schwannoma]].
'''Peripheral nerve sheath tumours''', abbreviated '''PNSTs''', are common in [[neuropathology]] and occasionally show-up elsewhere.  A very common PNST is the [[schwannoma]].


==Classification==
=Classification=
A classification:<ref name=pmid17893219>{{cite journal |author=Wippold FJ, Lubner M, Perrin RJ, Lämmle M, Perry A |title=Neuropathology for the neuroradiologist: Antoni A and Antoni B tissue patterns |journal=AJNR Am J Neuroradiol |volume=28 |issue=9 |pages=1633–8 |year=2007 |month=October |pmid=17893219 |doi=10.3174/ajnr.A0682 |url=http://www.ajnr.org/cgi/reprint/28/9/1633}}</ref>
A classification:<ref name=pmid17893219>{{cite journal |author=Wippold FJ, Lubner M, Perrin RJ, Lämmle M, Perry A |title=Neuropathology for the neuroradiologist: Antoni A and Antoni B tissue patterns |journal=AJNR Am J Neuroradiol |volume=28 |issue=9 |pages=1633–8 |year=2007 |month=October |pmid=17893219 |doi=10.3174/ajnr.A0682 |url=http://www.ajnr.org/cgi/reprint/28/9/1633}}</ref>
*Benign:
*Benign:
**Schwannoma.
**[[Schwannoma]].
**Neurofibroma.
**[[Neurofibroma]].
**Perineurioma.
**[[Perineurioma]].
**Traumatic neuroma.
**[[Traumatic neuroma]].
*Malignant:
*Malignant:
**Malignant peripheral nerve sheath tumour (MPNST).
**[[Malignant peripheral nerve sheath tumour]] (MPNST).


=Specific diagnoses=
==Schwannoma==  
==Schwannoma==  
===General===
{{Main|Schwannoma}}
*A common [[neuropathology]] [[CNS tumours|tumour]] that occasionally shows-up elsewhere.
*Tumour of tissue surrounding a nerve.
**Axons adjacent to the tumour are normal... but may be compressed.
*May be a part of [[neurofibromatosis type 2]].


===Microscopic===
==Perineurioma==
Features:<ref name=pmid17893219>{{cite journal |author=Wippold FJ, Lubner M, Perrin RJ, Lämmle M, Perry A |title=Neuropathology for the neuroradiologist: Antoni A and Antoni B tissue patterns |journal=AJNR Am J Neuroradiol |volume=28 |issue=9 |pages=1633–8 |year=2007 |month=October |pmid=17893219 |doi=10.3174/ajnr.A0682 |url=http://www.ajnr.org/cgi/reprint/28/9/1633}}</ref>
{{Main|Perineurioma}}
*Antoni A:
**Cellular.
**'Fibrillary, polar, elongated'.
*Antoni B:
**Pauci-cellular.
**Loose microcystic tissue.
*Verocay bodies - paucinuclear area surrounded by nuclei.
*In the GI tract: classically have a ''peripheral lymphoid cuff''.<ref name=pmid15728600>{{cite journal |author=Levy AD, Quiles AM, Miettinen M, Sobin LH |title=Gastrointestinal schwannomas: CT features with clinicopathologic correlation |journal=AJR Am J Roentgenol |volume=184 |issue=3 |pages=797–802 |year=2005 |month=March |pmid=15728600 |doi= |url=http://www.ajronline.org/cgi/content/full/184/3/797}}</ref>


Notes:
==Traumatic neuroma==
*Tumour does ''not'' smear well.<ref>MUN. 24 November 2010.</ref>
:May be referred to as ''[[neuroma]]''.
*Antoni A: may look somewhat like scattered matchsticks.
{{Main|Traumatic neuroma}}


Micrographs:
==Palisaded encapsulated neuroma==
*[http://www.pathguy.com/~lulo/lulo0003.htm Antoni A (pathguy.com)].
*Abbreviated ''PEN''.
*[http://www.ajnr.org/cgi/content/full/28/9/1633/F8 Antoni A & Antoni B side-by-side (ajnr.org)].
*[[AKA]] ''palisaded and encapsulated neuroma''.
*[http://commons.wikimedia.org/wiki/File:Psammomatous_melanotic_schwannoma_-_high_mag.jpg Psammomatous melanotic schwannoma - high mag. (WC)].
*[[AKA]] ''solitary circumscribed neuroma''.


====Subtypes====
There are four:<ref name=pmid12792904>{{cite journal |author=Kurtkaya-Yapicier O, Scheithauer B, Woodruff JM |title=The pathobiologic spectrum of Schwannomas |journal=Histol. Histopathol. |volume=18 |issue=3 |pages=925–34 |year=2003 |month=July |pmid=12792904 |doi= |url=}}</ref>
#Conventional.
#*Most common.
#Cellular.
#*May mimic [[MPNST]].
#Plexiform.
#*May mimic [[MPNST]] if cellular - esp. in childhood.
#Melanotic.
#*May be confused with [[melanoma]].
#*Psammomatous form (''psammomatous melanotic schwannoma'') associated with a heritable disorder ([[Carney complex]]).
Notes:
*[[Carney complex]]:<ref name=pmid12792904/>
**Cutaneous lentigines.
**Myxomas (skin (subcutaneous), subcutanous, [[Cardiac tumours#Atrial myxoma|heart]]).
**Endocrine neoplasms.
===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>
*S-100 +ve.
*Glut1 +ve.
*CD34 +ve.
*Cytokeratins ~70% +ve.{{fact}}
*SOX10 +ve.<ref name=pmid18636017>{{cite journal |author=Nonaka D, Chiriboga L, Rubin BP |title=Sox10: a pan-schwannian and melanocytic marker |journal=Am. J. Surg. Pathol. |volume=32 |issue=9 |pages=1291–8 |year=2008 |month=September |pmid=18636017 |doi=10.1097/PAS.0b013e3181658c14 |url=}}</ref>
**-ve in [[synovial sarcoma]], [[rhabdomyosarcoma]], [[chondrosarcoma]].
==Perineurioma==
===General===
===General===
*Benign tumour derived from perineurial cells.
*Flesh-colour [[papule]] - classically on the face.<ref name=Ref_Derm536>{{Ref Derm|536}}</ref>
*Isolated finding - not associated with a systemic disease or malignancy.<ref name=pmid18718196>{{Cite journal  | last1 = Newman | first1 = MD. | last2 = Milgraum | first2 = S. | title = Palisaded encapsulated neuroma (PEN): an often misdiagnosed neural tumor. | journal = Dermatol Online J | volume = 14 | issue = 7 | pages = 12 | month =  | year = 2008 | doi =  | PMID = 18718196 }}</ref>
*Superficial skin papule.<ref>S. Sade. 8 September 2011.</ref>
*It is considered hyperplastic rather than neoplastic. <ref>Rosai & Ackermann, Surgical Pathology, 10th ed. p183</ref>


===Microscopic===
===Microscopic===
Features:<ref name=pc_neuri>URL: [http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675%2806%2970452-1 http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675%2806%2970452-1]. Accessed on: 13 May 2011.</ref>
Features:<ref name=Ref_Derm536>{{Ref Derm|536}}</ref>
*Long slender spindle cells with:
*Encapsulated dermal spindle cell lesion.
**Small spindle-shaped nuclei.
**Fasciular arrangement.
**Neural-type spindle cells:  
**#Not vacuolated.
**#Nuclei have pointy ends.
**#Sometimes epitheloid appearance.  
*Intralesional clefts.
**Useful to differentiate from schwannoma.


DDx:
DDx:
*Neuroma.
*[[Schwannoma]]:<ref name=Ref_Derm536>{{Ref Derm|536}}</ref>
*Neurofibroma.
**No intralesional clefts.
*Schwannoma.
**More variability in the cellularity.
**May be deep.


Image:
Other considerations:
*[http://www.pathconsultddx.com/pathCon/largeImage?pii=S1559-8675%2806%2970452-1&figureId=fig2 Perineurioma (pathconsultddx.com)].
*[[Leiomyoma]] - cytoplasm not vacuolated, nuclei more elliptical.  


===IHC===
Images:
Features:<ref name=pc_neuri>URL: [http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675%2806%2970452-1 http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675%2806%2970452-1]. Accessed on: 13 May 2011.</ref>
*[http://dermatology.cdlib.org/147/case_presentation/pen/2.jpg PEN (cdlib.org)].<ref name=pmid18718196>{{Cite journal  | last1 = Newman | first1 = MD. | last2 = Milgraum | first2 = S. | title = Palisaded encapsulated neuroma (PEN): an often misdiagnosed neural tumor. | journal = Dermatol Online J | volume = 14 | issue = 7 | pages = 12 | month =  | year = 2008 | doi =  | PMID = 18718196 }}</ref>
*S100 -ve.
 
*EMA +ve.
<gallery>
File:Palisaded_and_Encapsulated_Neuroma_(3952635881).jpg | Palisaded and encapsulated neuroma (Ed Uthman)
File:Palisaded_and_Encapsulated_Neuroma,_S-100_Immunostain_(3953412396).jpg| PEN, S-100 staining (Ed Uthman)


==Traumatic neuroma==
</gallery>
===General===
[[File:569 dp sl 1.png| Palisading/encapcuslated neuroma]]
*Consequence of trauma -- diagnosis requires history of trauma.
[[File:569 dp sl 2.png| Palisading/encapcuslated neuroma]]<br>
Palisading/encapsulated (Reed’s) neuroma. A. A dermal nodule shows an attenuated capsule (black arrows) about a fasciculated spindle cell lesion with artefactual clefts (green arrows). B. The bland spindled nuclei, amid clear cytoplasm with thin eosinophilic wisps, are often wavy (black arrows), with pointed ends (green arrows); leiomyomas have blunt ended nuclei and more eosinophilic cytoplasm.  These benign neoplasms, unlike neurofibromas, lack an association with neurofibromatosis.


===Microscopic===
===IHC===
Features:
Features:<ref name=pmid18718196/>
*Nerve with adjacent small organized micro-fascicles in collagen - as seen in regeneration.
*S100 +ve.
*EMA +ve (capsule of lesion).


==Neurofibroma==
==Neurofibroma==
===General===
{{Main|Neurofibroma}}
*May be a part of [[neurofibromatosis]] 1.
Includes discussion of ''plexiform neurofibroma''.
*Composed of Schwann cells, axons, fibrous material.<ref name=pmid17893219/>


===Microscopic===
==Neurothekeoma==
Features:
{{Main|Neurothekeoma}}
*Usu. a poorly circumscribed lesion.
*Moderate increase of cellularity.
*Spindle cells with wavy nuclei without pleomorphism.
*May be arranged in fascicles intermixed and with collagen.
*+/-Plexiform growth pattern - "bag of worms".<ref name=pmid17893219/>
 
DDx:
*[[Schwannoma]].
*[[Dermatofibrosarcoma protuberans]] (DFSP) - S-100 -ve, CD34 +ve.
*[[Ganglioneuroma]].


Image:
==Malignant peripheral nerve sheath tumour==
*[http://commons.wikimedia.org/wiki/File:Neurofibroma_(1).jpg Neurofibroma - low mag. (WC)].
{{Main|Malignant peripheral nerve sheath tumour}}
*[http://commons.wikimedia.org/wiki/File:Neurofibroma_(2).jpg Neurofibroma - high mag. (WC)].
*[http://commons.wikimedia.org/wiki/File:Neurofibroma_(3).jpg Neurofibroma - high mag. (WC)].


===IHC===
==Malignant triton tumour==
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>
*Abbreviated ''MTT''.
*S100 +ve.
*[[AKA]] ''malignant peripheral nerve sheath tumor with rhabdomyosarcomatous differentiation''.<ref name=pmid17149968>{{Cite journal | last1 = Stasik | first1 = CJ. | last2 = Tawfik | first2 = O. | title = Malignant peripheral nerve sheath tumor with rhabdomyosarcomatous differentiation (malignant triton tumor). | journal = Arch Pathol Lab Med | volume = 130 | issue = 12 | pages = 1878-81 | month = Dec | year = 2006 | doi = 10.1043/1543-2165(2006)130[1878:MPNSTW]2.0.CO;2 | PMID = 17149968 }}</ref>
*CD34 +ve.
*Glut1 +ve.
*EMA +ve/-ve.


==Neurothekeoma==
===General===
===General===
*Rare.
*Rare.
*Female > male.
*Considered to be a variant of ''[[MPNST]]''.
*Prognosis worse that conventional MPNST.<ref name=pmid17149968/>
**Five year survival ~14%.<ref name=pmid22253011>{{Cite journal  | last1 = McConnell | first1 = YJ. | last2 = Giacomantonio | first2 = CA. | title = Malignant triton tumors-complete surgical resection and adjuvant radiotherapy associated with improved survival. | journal = J Surg Oncol | volume =  | issue =  | pages =  | month = Jan | year = 2012 | doi = 10.1002/jso.23042 | PMID = 22253011 }}</ref>
*Diagnosis may require clinical information, i.e. individual has a history of [[neurofibromatosis type 1]] (NF1).


Note:
*A handful of ''benign triton tumours'' are reported; these are considered ''neuromuscular [[hamartoma]]s''.<ref name=pmid15814954>{{Cite journal  | last1 = Castro | first1 = DE. | last2 = Raghuram | first2 = K. | last3 = Phillips | first3 = CD. | title = Benign triton tumor of the trigeminal nerve. | journal = AJNR Am J Neuroradiol | volume = 26 | issue = 4 | pages = 967-9 | month = Apr | year = 2005 | doi =  | PMID = 15814954 }}
</ref>
===Microscopic===
===Microscopic===
Features:<ref name=pmid17325474>{{cite journal |author=Hornick JL, Fletcher CD |title=Cellular neurothekeoma: detailed characterization in a series of 133 cases |journal=Am. J. Surg. Pathol. |volume=31 |issue=3 |pages=329–40 |year=2007 |month=March |pmid=17325474 |doi=10.1097/01.pas.0000213360.03133.89 |url=}}</ref>
Features - Woodruff criteria - all three required:<ref name=pmid17149968/>
*Dermal spindle cell lesion.
# (a) Tumour arise from a peripheral nerve ''or'' (b) individual has [[NF1]] ''or'' (c) lesion a metastasis arising in the context of (a) or (b).
*+/-Inflammation around lesion.
# Schwann cell tumour characteristics.
# Rhabdomyoblasts.
#* Eccentric nucleus.
#* Moderate amount of eosinophilic cytoplasm.
#* +/-Cross-striations.  


Notes:
DDx:
*No atypia.
*[[Malignant peripheral nerve sheath tumour]].
*Mitoses rare/none.
*[[Adult fibrosarcoma]].
 
*[[Synovial sarcoma]].
Subtypes:<ref name=pmid10555009>{{cite journal |author=Wang AR, May D, Bourne P, Scott G |title=PGP9.5: a marker for cellular neurothekeoma |journal=Am. J. Surg. Pathol. |volume=23 |issue=11 |pages=1401–7 |year=1999 |month=November |pmid=10555009 |doi= |url=}}</ref>
*[[Rhabdomyosarcoma]].
*Cellular.
*[[Carcinosarcoma]].
*Myxoid.
*Intermediate.
 
DDx:
*[[Dermatofibroma]].
*Angiomatoid fibrous histiocytoma -- have cystic blood filled spaces, inflammation.<ref>URL: [http://surgpathcriteria.stanford.edu/softfib/angiomatoid_fibrous_histiocytoma/ http://surgpathcriteria.stanford.edu/softfib/angiomatoid_fibrous_histiocytoma/]. Accessed on: 11 May 2011.</ref>
 
Image(s):
*[http://en.wikipedia.org/wiki/File:Neurothekeoma2.JPG Neurothekeoma (WP)].


===IHC===
===IHC===
Features:<ref name=pmid17325474/>
*NKI/C3 ([[AKA]] NKI-C3) +ve.
*NSE +/-ve.
Others:<ref name=pmid17592278>{{cite journal |author=Fetsch JF, Laskin WB, Hallman JR, Lupton GP, Miettinen M |title=Neurothekeoma: an analysis of 178 tumors with detailed immunohistochemical data and long-term patient follow-up information |journal=Am. J. Surg. Pathol. |volume=31 |issue=7 |pages=1103–14 |year=2007 |month=July |pmid=17592278 |doi=10.1097/PAS.0b013e31802d96af |url=}}</ref>
*Vimentin +ve.
*CD10 +ve.
*Microphthalmia transcription factor +ve.
*PGP9.5 +ve.
Exclusionary:
*S100 -ve.
**Exclude other peripheral nerve sheath tumours. (???)
==Malignant peripheral nerve sheath tumours==
===General===
*Malignant - as the name implies.
*Usu. assoc. with a peripheral nerve.{{Fact}}
===Microscopic===
Features:
Features:
*Cellular.
*S100 +ve/-ve -- usu. focal if positive.<ref name=pmid17149968/>
*Nuclear atypia.
*Leu-7 +ve/-ve.
*Mitoses.
*Myelin basic protein +ve/-ve.
 
DDx:
*Cellular schwannoma.
*Plexiform schwannoma.


Image(s):
Rhabdomyoblastic differentiation:<ref name=pmid17149968/>
*[http://commons.wikimedia.org/wiki/File:Malignant_peripheral_nerve_sheath_tumour_-_intermed_mag.jpg MPNST - intermed. mag. (WC)].
*Desmin.
*[http://commons.wikimedia.org/wiki/File:Malignant_peripheral_nerve_sheath_tumour_-_high_mag.jpg MPNST - high mag. (WC)].
*Actin.
*Myogenin.


Notes:
===EM===
*May be diagnosed in a poorly diff. tumour if patient has NF1.
*+/-Sarcomeres.<ref name=pmid17149968/>
 
====Grading====
*Can be graded histologically,<ref name=pmid14508395>{{cite journal |author=Zhou H, Coffin CM, Perkins SL, Tripp SR, Liew M, Viskochil DH |title=Malignant peripheral nerve sheath tumor: a comparison of grade, immunophenotype, and cell cycle/growth activation marker expression in sporadic and neurofibromatosis 1-related lesions |journal=Am. J. Surg. Pathol. |volume=27 |issue=10 |pages=1337–45 |year=2003 |month=October |pmid=14508395 |doi= |url=}}</ref> and this is prognostic.<ref name=pmid16923196>{{cite journal |author=Kar M, Deo SV, Shukla NK, ''et al.'' |title=Malignant peripheral nerve sheath tumors (MPNST)--clinicopathological study and treatment outcome of twenty-four cases |journal=World J Surg Oncol |volume=4 |issue= |pages=55 |year=2006 |pmid=16923196 |pmc=1560134 |doi=10.1186/1477-7819-4-55 |url=}}</ref>
 
Sarcoma grading system<ref name=pmid6693192>{{cite journal |author=Trojani M, Contesso G, Coindre JM, ''et al.'' |title=Soft-tissue sarcomas of adults; study of pathological prognostic variables and definition of a histopathological grading system |journal=Int. J. Cancer |volume=33 |issue=1 |pages=37–42 |year=1984 |month=January |pmid=6693192 |doi= |url=}}</ref> - based on:
*Tumour differentiation.
*Mitotic rate.
*[[Necrosis]].
 
===IHC===
Features:<ref name=pmid18636017>{{cite journal |author=Nonaka D, Chiriboga L, Rubin BP |title=Sox10: a pan-schwannian and melanocytic marker |journal=Am. J. Surg. Pathol. |volume=32 |issue=9 |pages=1291–8 |year=2008 |month=September |pmid=18636017 |doi=10.1097/PAS.0b013e3181658c14 |url=}}</ref>  
*S-100 +ve ~ 30% of tumours.
*SOX10 +ve ~ 50% of tumours.


Others:<ref name=pmid14508395>{{cite journal |author=Zhou H, Coffin CM, Perkins SL, Tripp SR, Liew M, Viskochil DH |title=Malignant peripheral nerve sheath tumor: a comparison of grade, immunophenotype, and cell cycle/growth activation marker expression in sporadic and neurofibromatosis 1-related lesions |journal=Am. J. Surg. Pathol. |volume=27 |issue=10 |pages=1337–45 |year=2003 |month=October |pmid=14508395 |doi= |url=}}</ref>
==Morton neuroma==
*p53.
:[[AKA]] ''plantar interdigital neuroma''.<ref name=pmid22995258>{{Cite journal | last1 = Makki | first1 = D. | last2 = Haddad | first2 = BZ. | last3 = Mahmood | first3 = Z. | last4 = Shahid | first4 = MS. | last5 = Pathak | first5 = S. | last6 = Garnham | first6 = I. | title = Efficacy of corticosteroid injection versus size of plantar interdigital neuroma. | journal = Foot Ankle Int | volume = 33 | issue = 9 | pages = 722-6 | month = Sep | year = 2012 | doi = DOI: 10.3113/FAI.2012.0722 | PMID = 22995258 }}</ref>
*p16.
{{Main|Morton neuroma}}
*p27.
*MIB-1.


==See also==
=See also=
*[[Neuropathology]].
*[[Neuropathology]].
*[[Gastrointestinal pathology]].
*[[Gastrointestinal pathology]].


==References==
=References=
{{Reflist|2}}
{{Reflist|2}}


[[Category:Neuropathology]]
[[Category:Neuropathology]]
[[Category:Peripheral nerve sheath tumours]]

Latest revision as of 14:18, 29 August 2018

Peripheral nerve sheath tumours, abbreviated PNSTs, are common in neuropathology and occasionally show-up elsewhere. A very common PNST is the schwannoma.

Classification

A classification:[1]

Specific diagnoses

Schwannoma

Main article: Schwannoma

Perineurioma

Main article: Perineurioma

Traumatic neuroma

May be referred to as neuroma.
Main article: Traumatic neuroma

Palisaded encapsulated neuroma

  • Abbreviated PEN.
  • AKA palisaded and encapsulated neuroma.
  • AKA solitary circumscribed neuroma.

General

  • Flesh-colour papule - classically on the face.[2]
  • Isolated finding - not associated with a systemic disease or malignancy.[3]
  • Superficial skin papule.[4]
  • It is considered hyperplastic rather than neoplastic. [5]

Microscopic

Features:[2]

  • Encapsulated dermal spindle cell lesion.
    • Fasciular arrangement.
    • Neural-type spindle cells:
      1. Not vacuolated.
      2. Nuclei have pointy ends.
      3. Sometimes epitheloid appearance.
  • Intralesional clefts.
    • Useful to differentiate from schwannoma.

DDx:

  • Schwannoma:[2]
    • No intralesional clefts.
    • More variability in the cellularity.
    • May be deep.

Other considerations:

  • Leiomyoma - cytoplasm not vacuolated, nuclei more elliptical.

Images:

  • Palisaded and encapsulated neuroma (Ed Uthman)

  • PEN, S-100 staining (Ed Uthman)

Palisading/encapcuslated neuroma Palisading/encapcuslated neuroma
Palisading/encapsulated (Reed’s) neuroma. A. A dermal nodule shows an attenuated capsule (black arrows) about a fasciculated spindle cell lesion with artefactual clefts (green arrows). B. The bland spindled nuclei, amid clear cytoplasm with thin eosinophilic wisps, are often wavy (black arrows), with pointed ends (green arrows); leiomyomas have blunt ended nuclei and more eosinophilic cytoplasm. These benign neoplasms, unlike neurofibromas, lack an association with neurofibromatosis.

IHC

Features:[3]

  • S100 +ve.
  • EMA +ve (capsule of lesion).

Neurofibroma

Main article: Neurofibroma

Includes discussion of plexiform neurofibroma.

Neurothekeoma

Main article: Neurothekeoma

Malignant peripheral nerve sheath tumour

Main article: Malignant peripheral nerve sheath tumour

Malignant triton tumour

  • Abbreviated MTT.
  • AKA malignant peripheral nerve sheath tumor with rhabdomyosarcomatous differentiation.[6]

General

  • Rare.
  • Considered to be a variant of MPNST.
  • Prognosis worse that conventional MPNST.[6]
    • Five year survival ~14%.[7]
  • Diagnosis may require clinical information, i.e. individual has a history of neurofibromatosis type 1 (NF1).

Note:

  • A handful of benign triton tumours are reported; these are considered neuromuscular hamartomas.[8]

Microscopic

Features - Woodruff criteria - all three required:[6]

  1. (a) Tumour arise from a peripheral nerve or (b) individual has NF1 or (c) lesion a metastasis arising in the context of (a) or (b).
  2. Schwann cell tumour characteristics.
  3. Rhabdomyoblasts.
    • Eccentric nucleus.
    • Moderate amount of eosinophilic cytoplasm.
    • +/-Cross-striations.

DDx:

IHC

Features:

  • S100 +ve/-ve -- usu. focal if positive.[6]
  • Leu-7 +ve/-ve.
  • Myelin basic protein +ve/-ve.

Rhabdomyoblastic differentiation:[6]

  • Desmin.
  • Actin.
  • Myogenin.

EM

  • +/-Sarcomeres.[6]

Morton neuroma

AKA plantar interdigital neuroma.[9]
Main article: Morton neuroma

See also

References

  1. ↑ Wippold FJ, Lubner M, Perrin RJ, Lämmle M, Perry A (October 2007). "Neuropathology for the neuroradiologist: Antoni A and Antoni B tissue patterns". AJNR Am J Neuroradiol 28 (9): 1633–8. doi:10.3174/ajnr.A0682. PMID 17893219. http://www.ajnr.org/cgi/reprint/28/9/1633.
  2. ↑ 2.0 2.1 2.2 Busam, Klaus J. (2009). Dermatopathology: A Volume in the Foundations in Diagnostic Pathology Series (1st ed.). Saunders. pp. 536. ISBN 978-0443066542.
  3. ↑ 3.0 3.1 3.2 Newman, MD.; Milgraum, S. (2008). "Palisaded encapsulated neuroma (PEN): an often misdiagnosed neural tumor.". Dermatol Online J 14 (7): 12. PMID 18718196.
  4. ↑ S. Sade. 8 September 2011.
  5. ↑ Rosai & Ackermann, Surgical Pathology, 10th ed. p183
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 Stasik, CJ.; Tawfik, O. (Dec 2006). "Malignant peripheral nerve sheath tumor with rhabdomyosarcomatous differentiation (malignant triton tumor).". Arch Pathol Lab Med 130 (12): 1878-81. doi:10.1043/1543-2165(2006)130[1878:MPNSTW]2.0.CO;2. PMID 17149968.
  7. ↑ McConnell, YJ.; Giacomantonio, CA. (Jan 2012). "Malignant triton tumors-complete surgical resection and adjuvant radiotherapy associated with improved survival.". J Surg Oncol. doi:10.1002/jso.23042. PMID 22253011.
  8. ↑ Castro, DE.; Raghuram, K.; Phillips, CD. (Apr 2005). "Benign triton tumor of the trigeminal nerve.". AJNR Am J Neuroradiol 26 (4): 967-9. PMID 15814954.
  9. ↑ Makki, D.; Haddad, BZ.; Mahmood, Z.; Shahid, MS.; Pathak, S.; Garnham, I. (Sep 2012). "Efficacy of corticosteroid injection versus size of plantar interdigital neuroma.". Foot Ankle Int 33 (9): 722-6. doi:DOI: 10.3113/FAI.2012.0722. PMID 22995258.
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