Difference between revisions of "Soft tissue lesions"

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'''Soft tissue lesions''' strike fear in many pathologists as they are uncommon and may be difficult to diagnose.  
'''Soft tissue lesions''' strike fear in many pathologists as they are uncommon and may be difficult to diagnose. Malignant soft tissue lesions, i.e. [[cancer|cancerous]] soft tissue lesions, are usually '''sarcomas'''. Sarcomas are malignancies derived from mesenchymal tissue. 


=Introduction=
=Introduction=
==WHO classification of soft tissue lesions/tumours==
==WHO classification of soft tissue lesions/tumours==
===Morphologic grouping<ref name=Ref_WMSP601-3>{{Ref WMSP|601-3}}</ref>===
===Morphologic grouping===
These include:<ref name=Ref_WMSP601-3>{{Ref WMSP|601-3}}</ref>
#[[Adipocytic tumours]].
#[[Adipocytic tumours]].
#[[Fibroblastic/myofibroblastic tumours]].
#[[Fibroblastic/myofibroblastic tumours]].
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#[[Soft tissue lesions#Tumours of uncertain differentiation|Tumours of uncertain differentiation]].
#[[Soft tissue lesions#Tumours of uncertain differentiation|Tumours of uncertain differentiation]].


===Biologic potential grouping<ref>{{Ref WMSP|598-604}}</ref>===
===Biologic potential grouping===
These include:<ref>{{Ref WMSP|598-604}}</ref>
#Benign.
#Benign.
#Intermediate (locally aggressive).
#Intermediate (locally aggressive).
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*Once upon a time almost everything was called ''malignant fibrous histiocytoma''; thus, it is listed as a common entity in some publications.
*Once upon a time almost everything was called ''malignant fibrous histiocytoma''; thus, it is listed as a common entity in some publications.


===Most common:<ref name=pmid17976362>{{cite journal |author=Skubitz KM, D'Adamo DR |title=Sarcoma |journal=Mayo Clin. Proc. |volume=82 |issue=11 |pages=1409–32 |year=2007 |month=November |pmid=17976362 |doi= |url= http://www.mayoclinicproceedings.com/content/82/11/1409.long}}</ref>===
Most common:<ref name=pmid17976362>{{cite journal |author=Skubitz KM, D'Adamo DR |title=Sarcoma |journal=Mayo Clin. Proc. |volume=82 |issue=11 |pages=1409–32 |year=2007 |month=November |pmid=17976362 |doi= |url= http://www.mayoclinicproceedings.com/content/82/11/1409.long}}</ref>
*Liposarcoma.
*Liposarcoma.
*Leiomyosarcoma.
*Leiomyosarcoma.
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*Many tumours in soft tissue pathology are diagnosed inconjunction with the finding of [[chromosomal translocations]].
*Many tumours in soft tissue pathology are diagnosed inconjunction with the finding of [[chromosomal translocations]].


==Histologic patterns==
==Morphohistologic patterns==
{{Main|Morphologic patterns}}
{| class="wikitable sortable" style="margin-left:auto;margin-right:auto"
{| class="wikitable sortable" style="margin-left:auto;margin-right:auto"
! Name
! Name
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! DDx
! DDx
! Image(s)
! Image(s)
! Other
|-
|-
| Storiform, [[AKA]] patternless pattern<ref name=pmid9704618>{{cite journal |author=Mangano WE, Cagle PT, Churg A, Vollmer RT, Roggli VL |title=The diagnosis of desmoplastic malignant mesothelioma and its distinction from fibrous pleurisy: a histologic and immunohistochemical analysis of 31 cases including p53 immunostaining |journal=Am. J. Clin. Pathol. |volume=110 |issue=2 |pages=191–9 |year=1998 |month=August |pmid=9704618 |doi= |url=}}</ref>
| Storiform, [[AKA]] patternless pattern<ref name=pmid9704618>{{cite journal |author=Mangano WE, Cagle PT, Churg A, Vollmer RT, Roggli VL |title=The diagnosis of desmoplastic malignant mesothelioma and its distinction from fibrous pleurisy: a histologic and immunohistochemical analysis of 31 cases including p53 immunostaining |journal=Am. J. Clin. Pathol. |volume=110 |issue=2 |pages=191–9 |year=1998 |month=August |pmid=9704618 |doi= |url=}}</ref>
| whorled, cartwheel-like arrangement
| whorled, cartwheel-like arrangement
| [[pleomorphic undifferentiated sarcoma]], [[solitary fibrous tumour]], [[dermatofibrosarcoma protuberans]], [[dermatofibroma]]<ref name=pmid224569>{{cite journal |author=Meister P, Höhne N, Konrad E, Eder M |title=Fibrous histiocytoma: an analysis of the storiform pattern |journal=Virchows Arch A Pathol Anat Histol |volume=383 |issue=1 |pages=31–41 |year=1979 |month=July |pmid=224569 |doi= |url=}}</ref>
| [[pleomorphic undifferentiated sarcoma]], [[solitary fibrous tumour]], [[dermatofibrosarcoma protuberans]], [[dermatofibroma]]<ref name=pmid224569>{{cite journal |author=Meister P, Höhne N, Konrad E, Eder M |title=Fibrous histiocytoma: an analysis of the storiform pattern |journal=Virchows Arch A Pathol Anat Histol |volume=383 |issue=1 |pages=31–41 |year=1979 |month=July |pmid=224569 |doi= |url=}}</ref>
| [http://commons.wikimedia.org/w/index.php?title=File:Storiform_pattern_-_intermed_mag.jpg intermed. mag.], [http://commons.wikimedia.org/wiki/File:Storiform_pattern_-_very_high_mag.jpg very high mag.]
| [[Image:Storiform_pattern_-_intermed_mag.jpg |thumb|center|150px| Patternless pattern. (WC)]]
| other ?
|-
|-
| Herring bone
| Herring bone
| like herring bone (technique) for climbing a hill in cross country skiing; books on a shelf, where they have partially fallen over -- on the one shelf to the left and the one below to the right
| like herring bone (technique) for climbing a hill in cross country skiing; books on a shelf, where they have partially fallen over -- on the one shelf to the left and the one below to the right
| [[fibrosarcoma]], [[synovial sarcoma]], [[MPNST]]
| [[fibrosarcoma]], [[synovial sarcoma]], [[MPNST]]
| [http://commons.wikimedia.org/wiki/File:Malignant_peripheral_nerve_sheath_tumour_-_intermed_mag.jpg intermed. mag.], [http://commons.wikimedia.org/wiki/File:Malignant_peripheral_nerve_sheath_tumour_-_high_mag.jpg high mag.]  
| [[Image:Malignant_peripheral_nerve_sheath_tumour_-_intermed_mag.jpg |thumb|center|150px |Herring bone. (WC)]]  
| other ?
|-
|-
| Fasicular
| Fascicular
| the long axis of the (spindle) cells are perpendicular to one another in adjacent bundles of cells
| the long axis of the (spindle) cells are perpendicular to one another in adjacent bundles of cells
| [[leiomyoma]], [[leiomyosarcoma]]
| [[leiomyoma]], [[leiomyosarcoma]]
| [http://commons.wikimedia.org/wiki/File:Cutaneous_leiomyosarcoma_-_a_-_intermed_mag.jpg intermed. mag.], [http://commons.wikimedia.org/wiki/File:Cutaneous_leiomyosarcoma_-_high_mag.jpg high mag.]
| [[Image:Cutaneous_leiomyosarcoma_-_high_mag.jpg |thumb|center|150px| Fascicular pattern. (WC)]]
| other ?
|-
|-
| Biphasic
| Biphasic
| nests of cells and stroma
| nests of cells and stroma
| [[synovial sarcoma]], [[DSRCT]], [[alveolar RMS]]
| [[synovial sarcoma]], [[DSRCT]], [[alveolar RMS]]
| [http://commons.wikimedia.org/wiki/File:Desmoplastic_small_round_cell_tumour_-_high_mag.jpg DSRCT - high mag. (WC)]
| [[Image:Desmoplastic_small_round_cell_tumour_-_high_mag.jpg|thumb|center|150px| DSRCT. (WC)]]
| other ?
|- <!--
|- <!--
| name ?
| name ?
| description ?
| description ?
| DDx ?
| DDx ?
| image ?
| image ? -->
| other ? -->
|}
|}


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===French system===
===French system===
Overview:<ref name=pmid8996162/><ref name=uscap_stp>URL: [http://www.cap.org/apps/docs/committees/cancer/cancer_protocols/2011/SoftTissue_11protocol.pdf http://www.cap.org/apps/docs/committees/cancer/cancer_protocols/2011/SoftTissue_11protocol.pdf]. Accessed on: 12 April 2011.</ref>
*Formally known as the grading system from the ''French Federation of Cancer Centres Sarcoma Group'' (FNCLCC).
 
====Overview====
Components - overview:<ref name=pmid8996162/><ref name=uscap_stp>URL: [http://www.cap.org/apps/docs/committees/cancer/cancer_protocols/2011/SoftTissue_11protocol.pdf http://www.cap.org/apps/docs/committees/cancer/cancer_protocols/2011/SoftTissue_11protocol.pdf]. Accessed on: 12 April 2011.</ref>
#Differentiation (score 1-3).
#Differentiation (score 1-3).
#*De facto, this is mostly the ''histologic type''.
#*De facto, this is mostly the ''histologic type''.
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*Well-differentiated liposarcoma = 1.
*Well-differentiated liposarcoma = 1.
*Myxoid liposarcoma = 2.
*Myxoid liposarcoma = 2.
*Conventional liposarcoma = 2.
*Conventional [[liposarcoma]] = 2.
*Fibrosarcoma = 2.
*Fibrosarcoma = 2.
*Myxofibrosarcoma =2.
*[[Myxofibrosarcoma]] =2.


A group of tumours is not graded:<ref name=uscap_stp/>
A group of tumours is not graded:<ref name=uscap_stp/>
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*[[Alveolar soft part sarcoma]].
*[[Alveolar soft part sarcoma]].
*[[Clear cell sarcoma]].
*[[Clear cell sarcoma]].
*Extraskeletal myxoid chondrosarcoma.
*[[Extraskeletal myxoid chondrosarcoma]].


=====Mitotic rate=====
=====Mitotic rate=====
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*Cellularity (cells/matrix) > 50%.
*Cellularity (cells/matrix) > 50%.
*Necrosis >15% - microscopic (without targeting necrosis grossly) ''or'' grossly.
*Necrosis >15% - microscopic (without targeting necrosis grossly) ''or'' grossly.
==Stage==
{{Main|Cancer staging systems}}
===Lymph node metastases in sarcomas===
{{Main|Lymph node metastasis}}
*[[Lymph node]] (LN) spread is uncommon in sarcomas; [[lymph node metastases]] are seen in <3% of cases.<ref name=pmid8424704>{{Cite journal  | last1 = Fong | first1 = Y. | last2 = Coit | first2 = DG. | last3 = Woodruff | first3 = JM. | last4 = Brennan | first4 = MF. | title = Lymph node metastasis from soft tissue sarcoma in adults. Analysis of data from a prospective database of 1772 sarcoma patients. | journal = Ann Surg | volume = 217 | issue = 1 | pages = 72-7 | month = Jan | year = 1993 | doi =  | PMID = 8424704 | PMC = 1242736}}</ref>
**Many sarcomas are reported in LNs.
***According to the [[CAP checklist]] for soft tissue<ref>URL: [http://www.cap.org/apps/docs/committees/cancer/cancer_protocols/2011/SoftTissue_11protocol.pdf http://www.cap.org/apps/docs/committees/cancer/cancer_protocols/2011/SoftTissue_11protocol.pdf]. Accessed on: 28 March 2012.</ref> the most common are: [[epithelioid sarcoma]] and [[clear cell sarcoma]].
***According to Fong ''et al.''<ref name=pmid8424704/> the most commonly is: angiosarcoma.
Sarcomas more likely to be found in the lymph nodes - mnemonic ''RACE For MS'':<ref>URL: [http://www.aippg.net/forum/f21/surgery-mnemonics-79897/ http://www.aippg.net/forum/f21/surgery-mnemonics-79897/]. Accessed on: 23 March 2012.</ref>
*[[rhabdomyosarcoma|'''R'''habdomyosarcoma]]
*[[Angiosarcoma|'''A'''ngiosarcoma]].
*[[clear cell sarcoma|'''C'''lear cell sarcoma]].
*[[epithelioid sarcoma|'''E'''pitheliod sarcoma]].
*[[fibrosarcoma|'''F'''ibrosarcoma]].
*[[pleomorphic undifferentiated sarcoma|'''M'''alignant fibrous histiocytoma (pleomorphic undifferentiated sarcoma)]].
*[[synovial sarcoma|'''S'''ynovial cell sarcoma]].
==DDx by history/site==
===Retroperiteum===
#[[Liposarcoma]].
#[[Undifferentiated pleomorphic sarcoma]].
#[[Leiomyosarcoma]].
#[[MPNST]].
Note:
[[Synovial sarcoma]] and [[fibrosarcoma]] are very rare in the retroperitoneum.
===Young person - extremity sarcoma===
#[[Epithelioid sarcoma]].
#[[Synovial sarcoma]].
==Gross characteristics==
*Usually non-specific.
*Most sarcomas have a pushing border.
**If there is an infiltrative border think: (1) fibromatosis, (2) carcinoma.


=Adipocytic tumours=
=Adipocytic tumours=
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=Smooth muscle tumours=
=Smooth muscle tumours=
{{Main|Smooth muscle tumours}}
IHC markers: desmin, SMA, H-caldemsin (most specific).


==Leiomyosarcoma==
==Leiomyosarcoma==
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=Fibrohistiocytic tumours=
=Fibrohistiocytic tumours=
''Fibrohistiocytic'' refers (only) to the histomorphologic appearance and therefore may be written in quotation marks; these tumours are not derived from histiocytes (or tissue macrophages), as the name implies.<ref name=pmid20055912>{{Cite journal  | last1 = Luzar | first1 = B. | last2 = Calonje | first2 = E. | title = Cutaneous fibrohistiocytic tumours - an update. | journal = Histopathology | volume = 56 | issue = 1 | pages = 148-65 | month = Jan | year = 2010 | doi = 10.1111/j.1365-2559.2009.03447.x | PMID = 20055912 }}</ref>
==Pleomorphic undifferentiated sarcoma==
==Pleomorphic undifferentiated sarcoma==
*Abbreviated ''PUS''.
*Abbreviated ''PUS''.
*[[AKA]] ''Undifferentiated pleomorphic sarcoma''.
*[[AKA]] ''Undifferentiated pleomorphic sarcoma'', abbreviated ''UPS''.
*Previously known as ''malignant fibrous histiocytoma'', abbreviated ''MFH''.<ref>URL: [http://sarcomahelp.org/learning_center/mfh.html http://sarcomahelp.org/learning_center/mfh.html]. Accessed on: 8 April 2011.</ref>
*Previously known as ''malignant fibrous histiocytoma'', abbreviated ''MFH''.<ref>URL: [http://sarcomahelp.org/learning_center/mfh.html http://sarcomahelp.org/learning_center/mfh.html]. Accessed on: 8 April 2011.</ref>
 
{{Main|Pleomorphic undifferentiated sarcoma}}
===General===
*Common sarcoma.
*Usu. deep tissue of the trunk and extremities.
*A diagnosis of exclusion<ref name=pmid19671033>{{cite journal |author=Matushansky I, Charytonowicz E, Mills J, Siddiqi S, Hricik T, Cordon-Cardo C |title=MFH classification: differentiating undifferentiated pleomorphic sarcoma in the 21st Century |journal=Expert Rev Anticancer Ther |volume=9 |issue=8 |pages=1135–44 |year=2009 |month=August |pmid=19671033 |pmc=3000413 |doi=10.1586/era.09.76 |url=}}</ref> / wastebasket for unclassifiable high grade sarcomas.
 
===Microscopic===
Features:<ref name=Ref_WMSP_613>{{Ref WMSP|613}}</ref>
*Storiform pattern ([[AKA]] ''patternless pattern'') - '''key feature'''.
*Marked [[nuclear pleomorphism]] '''key feature'''.
**Variation is nuclear size, nuclear shape and nuclear staining (esp. hyperchromasia).
*Mitoses - abundant; atypical mitoses common.
*Necrosis (common).
*Mix of spindle cells and epithelioid cells.
 
Other findings:
*+/-Giant cells (see subclassification).
*+/-Inflammation (see subclassification).
**Neutrophils.
**Eosinophils.
 
Image:
*[http://commons.wikimedia.org/w/index.php?title=File:Pleomorphic_undifferentiated_sarcoma_-_very_high_mag.jpg PUS - high mag. (WC)].
*[http://commons.wikimedia.org/wiki/File:Pleomorphic_undifferentiated_sarcoma_-_intermed_mag.jpg PUS - intermed. mag. (WC)].
 
====Subclassification====
Pleomorphic sarcoma (PS) is subclassified the following way:<ref name=Ref_WMSP_613-4>{{Ref WMSP|613-4}}</ref>
*PS with giant cells.
*PS with inflammation.
*PUS (not otherwise specified) - wastebasket diagnosis; if neither of the above two apply.


=Fibroblastic/myofibroblastic tumours=
=Fibroblastic/myofibroblastic tumours=
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=Tumours of uncertain differentiation=
=Tumours of uncertain differentiation=
==Extrarenal malignant rhabdoid tumour==
==Angiomatoid fibrous histiocytoma==
*Essentially identical to ''renal malignant rhabdoid tumour''.<ref name=Ref_WMSP627>{{Ref WMSP|627}}</ref>
{{Main|Angiomatoid fibrous histiocytoma}}
===General===
 
*Usu. children < 2 years old.
==Aggressive angiomyxoma==
*Very poor prognosis.
*[[AKA]] deep aggressive angiomyxoma.
*In the CNS it is known as ''[[atypical teratoid-rhabdoid tumour]]''.<ref name=Ref_WMSP627>{{Ref WMSP|627}}</ref>
{{Main|Aggressive angiomyxoma}}


===Microscopic===
==Angiomyofibroblastoma==
Features:<ref name=Ref_WMSP627>{{Ref WMSP|627}}</ref>
{{Main|Angiomyofibroblastoma}}
*Variable architecture.
*Round cells.
*Eccentric vesicular nucleus.
*Prominent [[nucleolus]] -- '''key feature'''.


===IHC===
==Extrarenal malignant rhabdoid tumour==
*INI1 (SMARCB1) -ve.
*Essentially identical to ''[[renal malignant rhabdoid tumour]]''.<ref name=Ref_WMSP627>{{Ref WMSP|627}}</ref>
**AKA BAF47.
{{Main|Extrarenal malignant rhabdoid tumour}}


==Ewing sarcoma/PNET==
==Ewing sarcoma/PNET==
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==Epithelioid sarcoma==
==Epithelioid sarcoma==
===General===
:Sarcomas with an epithelioid morphology are covered in ''[[epithelioid sarcomas]]''.
*Rare.
{{Main|Epithelioid sarcoma}}
*Adolescents, young adults.
 
Subclassification:<ref name=pmid9042279>{{cite journal |author=Guillou L, Wadden C, Coindre JM, Krausz T, Fletcher CD |title="Proximal-type" epithelioid sarcoma, a distinctive aggressive neoplasm showing rhabdoid features. Clinicopathologic, immunohistochemical, and ultrastructural study of a series |journal=Am. J. Surg. Pathol. |volume=21 |issue=2 |pages=130–46 |year=1997 |month=February |pmid=9042279 |doi= |url=}}</ref>
*Proximal type:
**More aggressive.
*Distal type:
 
===Microscopic===
Features:<ref>{{Ref WHOSTAB|205}}</ref>
*Epithelioid morphology and spindle morphology - which predominates is dependent on location (see subclassification).
*+/-Prominent nucleolus - '''distinctive feature'''.
*Zonal necrosis with irregular border.
**Descriptors: "Garland necrosis", necrosis with "scalloped border" = necrotic regions with irregular border.
 
Subclassification:<ref name=pmid9042279>{{cite journal |author=Guillou L, Wadden C, Coindre JM, Krausz T, Fletcher CD |title="Proximal-type" epithelioid sarcoma, a distinctive aggressive neoplasm showing rhabdoid features. Clinicopathologic, immunohistochemical, and ultrastructural study of a series |journal=Am. J. Surg. Pathol. |volume=21 |issue=2 |pages=130–46 |year=1997 |month=February |pmid=9042279 |doi= |url=}}</ref>
*Proximal-type (proximal location):
**More epithelioid.
*Distal-type (distal location):
**More spindled.
**Granuloma-like pattern.
 
DDx:
*Carcinoma.
*[[Rheumatoid nodule]].  
*[[Granuloma annulare]].
 
===IHC===
Features:<ref name=pmid10452506>{{cite journal |author=Miettinen M, Fanburg-Smith JC, Virolainen M, Shmookler BM, Fetsch JF |title=Epithelioid sarcoma: an immunohistochemical analysis of 112 classical and variant cases and a discussion of the differential diagnosis |journal=Hum. Pathol. |volume=30 |issue=8 |pages=934–42 |year=1999 |month=August |pmid=10452506 |doi= |url=}}</ref>
*INI1 (SMARCB1<ref>{{OMIM|601607}}</ref>) -ve.<ref name=pmid19997734>{{cite journal |author=Mentzel T |title=[Epithelioid sarcoma: morphologic variants and differential diagnosis] |language=German |journal=Pathologe |volume=31 |issue=2 |pages=135–41 |year=2010 |month=March |pmid=19997734 |doi=10.1007/s00292-009-1250-0 |url=}}</ref>
*Vimentin +ve.
*Various keratins +ve.
**Keratin 8, Keratin 19 +ve.
**34betaE12 +ve/-ve.
*CD34 +ve.
**Malignant rhabdoid tumour -ve.
 
Others:
*S100 -ve (r/o melanoma).


==Alveolar soft part sarcoma==
==Alveolar soft part sarcoma==
*Abbreviated ''ASPS''.
{{Main|Alveolar soft part sarcoma}}
===General===
*Adolescents/young adults.
*Children -- classically location: base of tongue and orbit.
 
===Microscopic===
Features:<ref name=Ref_WMSP627>{{Ref WMSP|627}}</ref>
*Arranged in nest/separated by thin septa; vaguely resembles alveoli (at low power).
*Large cells (~30-50 μm) with abundant eosinophilic cytoplasm.
*An eccentric nucleus.
*+/-Nucleolus.
 
Images:
*[http://commons.wikimedia.org/wiki/File:Alveolar_soft_part_sarcoma_-_low_mag.jpg ASPS - low mag. (WC)].
*[http://commons.wikimedia.org/wiki/File:Alveolar_soft_part_sarcoma_-_intermed_mag.jpg ASPS - intermed. mag. (WC)].
*[http://commons.wikimedia.org/wiki/File:Alveolar_soft_part_sarcoma_-2-_very_high_mag.jpg ASPS - very high mag. (WC)].
 
===Molecular===
*t(X;17)(p11.2;q25).<ref>{{OMIM|606243}}</ref>


==Desmoplastic small round cell tumour==
==Desmoplastic small round cell tumour==
*Abbreviated ''DSRCT''.
{{Main|Desmoplastic small round cell tumour}}
===General===
*Males > females.
*Usu. affects young adults.
*Typically retroperitoneal.
*Poor prognosis.
 
===Microscopic===
Features:<ref name=pmid10207460>{{cite journal |author=Pickhardt PJ, Fisher AJ, Balfe DM, Dehner LP, Huettner PC |title=Desmoplastic small round cell tumor of the abdomen: radiologic-histopathologic correlation |journal=Radiology |volume=210 |issue=3 |pages=633–8 |year=1999 |month=March |pmid=10207460 |doi= |url=http://radiology.rsna.org/content/210/3/633.full}}</ref>
#Broad bands of paucicellular fibrous stroma with:
#Small round cells in nests with an undulating sharp border.
#*The small round cells lack distinct nucleoli and have scant cytoplasm; they are ''[[small round cell tumour]]'' cells.
 
Notes:
*Usu. abundant mitoses.
*+/-Necrosis.
 
Images:
*[http://en.wikipedia.org/wiki/File:Desmoplastic_small_round_cell_tumour_-_intermed_mag.jpg DSRCT - intermed. mag. (WC)].
*[http://en.wikipedia.org/wiki/File:Desmoplastic_small_round_cell_tumour_-_very_high_mag.jpg DSRCT - very high mag. (WC)].
 
DDx:
*Metastatic [[germ cell tumour]] (DDx of location and age).
*[[Embryonal RMS]].
**It should be noted that DSRCT, like embryonal RMS, is +ve for desmin!
*Solid variant of [[alveolar RMS]].
**Nests in alveolar RMS have round edges.
 
===IHC===
Features:
*AE1/AE3 +ve.
*Desmin +ve.
*EMA +ve.
*Actin -ve.
*WT1 (N-terminal) -ve.
*WT1 (C-terminal) +ve.
*CD57 +ve.
 
===Molecular===
*t(11;22)(p13;q12).<ref name=pmid17964965>{{cite journal |author=Lee YS, Hsiao CH |title=Desmoplastic small round cell tumor: a clinicopathologic, immunohistochemical and molecular study of four patients |journal=J. Formos. Med. Assoc. |volume=106 |issue=10 |pages=854–60 |year=2007 |month=October |pmid=17964965 |doi=10.1016/S0929-6646(08)60051-0 |url=}}</ref><ref>{{cite journal |author=Lal DR, Su WT, Wolden SL, Loh KC, Modak S, La Quaglia MP |title=Results of multimodal treatment for desmoplastic small round cell tumors |journal=J. Pediatr. Surg. |volume=40 |issue=1 |pages=251–5 |year=2005 |month=January |pmid=15868593 |doi=10.1016/j.jpedsurg.2004.09.046 |url=http://www.dsrct.com/JPS%20Article.pdf}}</ref>


==Clear cell sarcoma==
==Clear cell sarcoma==
*Known among pathologists as "soft-tissue melanoma" and "melanoma of the soft parts", as it has a strong morphological resemblance.<ref name=pmid18300804>{{cite journal |author=Hisaoka M, Ishida T, Kuo TT, ''et al.'' |title=Clear cell sarcoma of soft tissue: a clinicopathologic, immunohistochemical, and molecular analysis of 33 cases |journal=Am. J. Surg. Pathol. |volume=32 |issue=3 |pages=452–60 |year=2008 |month=March |pmid=18300804 |doi=10.1097/PAS.0b013e31814b18fb |url=}}</ref>
{{Main|Clear cell sarcoma}}
**Molecular changes and origin distinct from melanoma.
*Incidence: rare soft tissue tumour.
 
===Clinical===
*Usually - deep soft tissue ''or'' extremities.
*Guarded prognosis.
*First described in 1965.<ref>URL: [http://www.informaworld.com/smpp/723576818-750600/ftinterface~db=all~content=a789166263~fulltext=713240928 http://www.informaworld.com/smpp/723576818-750600/ftinterface~db=all~content=a789166263~fulltext=713240928]. Accessed on: 5 May 2010.</ref>
 
===Microscopy===
Features:<ref name=pmid18300804/>
*Architecture: sheets or fascicular (bundles) arrangement.
*Cells: Spindle cells or epithelioid cells.
*Prominent nucleoli - basophilic - '''key feature'''.
*Fibrous septae.
*Uniform.
*+/-Binucleation.
 
DDx:
*[[Malignant melanoma]].
*[[PEComa]].
*Carcinoma.
 
Image:
*[http://commons.wikimedia.org/wiki/File:Clear_cell_sarcoma.Image12.jpg Clear cell sarcoma (WC)].
*[http://www.informaworld.com/ampp/image?path=/713690780/789166263/sonc_a_284443_o_f0003g.jpeg Clear cell sarcoma (informaworld.com)].
 
===IHC===
Features:<ref name=pmid18300804/>
*S100 +ve.
*HMB-45 +ve.
*Melan A (MART-1) +ve; sometimes -ve.
*BCL2 +ve.
*CD57 +ve (usually).
 
Keratins:
*EMA may be +ve.
*CAM5.2 -ve.
*AE1/AE3 -ve.
 
===Molecular studies===
*Chromosomal translocation t(12;22)(q13;q12).<ref name=pmid18300804/>
**Fusion transcripts:
***EWSR1-ATF1.
***EWSR1-CREB1 (GI tract associated).


==Synovial sarcoma==
==Synovial sarcoma==
===General===
{{Main|Synovial sarcoma}}
*Does not arise from cartilage.<ref name=Ref_WMSP627>{{Ref WMSP|627}}</ref>
**Usually close to a joint.
**Usually distal extremity.
*Young adults or adolescents.
*Poor prognosis.
 
===Microscopic===
Comes in three (histologic) flavours:<ref name=Ref_WMSP627>{{Ref WMSP|627}}</ref><ref>{{cite journal |author=Schaal CH, Navarro FC, Moraes Neto FA |title=Primary renal sarcoma with morphologic and immunohistochemical aspects compatible with synovial sarcoma |journal=Int Braz J Urol |volume=30 |issue=3 |pages=210–3 |year=2004 |pmid=15689250 |doi= |url=http://www.brazjurol.com.br/may_june_2004/Schaal_ing_210_213.htm}}</ref>
#Spindle cell sarcoma with features of hemangiopericytoma, i.e. staghorn vessels.
#Biphasic synovial sarcoma:
##Spindle cells with features of hemangiopericytoma.
##Epitheliod glands or nests.
#Primitive round cell type.
 
Features:
*[[Herring bone]] or [[vesicular pattern]].
*Spindle cells.
*+/-Glandular component.
 
DDx:
*[[MPNST]].
**Can be difficult.
 
Images:
*[http://commons.wikimedia.org/wiki/File:Monophasic_synovial_sarcoma_-_intermed_mag.jpg Monophasic synovial sarcoma with staghorn vessels - intermed. mag. (WC)].
*[http://www.scielo.br/img/revistas/ibju/v30n3/3a06f03.jpg Synovial sarcoma (scielo.br)].
*[http://www.humpath.com/spip.php?page=article&id_article=1965 Synovial sarcoma - collection of images (humpath.com)].
 
===IHC===
Features:<ref name=Ref_WMSP627>{{Ref WMSP|627}}</ref>
*Vimentin +ve.
*EMA +ve.
*BCL2 +ve.
*CD99 +ve.
 
Others:
*Beta-catenin +ve ~30-70%.<ref name=pmid16740029>{{cite journal |author=Horvai AE, Kramer MJ, O'Donnell R |title=Beta-catenin nuclear expression correlates with cyclin D1 expression in primary and metastatic synovial sarcoma: a tissue microarray study |journal=Arch. Pathol. Lab. Med. |volume=130 |issue=6 |pages=792–8 |year=2006 |month=June |pmid=16740029 |doi= |url=}}</ref>
*Cyclin D1 ~50%.<ref name=pmid16740029/><ref name=pmid15375433>{{cite journal |author=Ng TL, Gown AM, Barry TS, ''et al.'' |title=Nuclear beta-catenin in mesenchymal tumors |journal=Mod. Pathol. |volume=18 |issue=1 |pages=68–74 |year=2005 |month=January |pmid=15375433 |doi=10.1038/modpathol.3800272 |url=}}</ref>
*TLE1 +ve nuclear staining; not specific for synovial sarcoma.<ref name=pmid19363472>{{cite journal |author=Kosemehmetoglu K, Vrana JA, Folpe AL |title=TLE1 expression is not specific for synovial sarcoma: a whole section study of 163 soft tissue and bone neoplasms |journal=Mod. Pathol. |volume=22 |issue=7 |pages=872–8 |year=2009 |month=July |pmid=19363472 |doi=10.1038/modpathol.2009.47 |url=http://www.nature.com/modpathol/journal/v22/n7/full/modpathol200947a.html}}</ref><ref>{{cite journal |author=Seo SW, Lee H, Lee HI, Kim HS |title=The role of TLE1 in synovial sarcoma |journal=J Orthop Res |volume= |issue= |pages= |year=2011 |month=February |pmid=21319215 |doi=10.1002/jor.21318 |url=}}</ref>
 
Notes:
*Synovial sarcoma & MPNST:
**Both +ve: PGP9.5 (UCHL1<ref>{{OMIM|191342}}</ref>), S100, NGFR, CD56, CD99, vimentin.
**Synovial +ve: EMA, keratin, BCL2, TLE1.
**MPNST +ve: nestin, CD34.
 
Trivia:
*PGP in ''PGP9.5'' = protein gene product.<ref name=pmid6343558>{{Cite journal  | last1 = Doran | first1 = JF. | last2 = Jackson | first2 = P. | last3 = Kynoch | first3 = PA. | last4 = Thompson | first4 = RJ. | title = Isolation of PGP 9.5, a new human neurone-specific protein detected by high-resolution two-dimensional electrophoresis. | journal = J Neurochem | volume = 40 | issue = 6 | pages = 1542-7 | month = Jun | year = 1983 | doi =  | PMID = 6343558 }}</ref>
 
===Molecular pathology===
Associated [[translocation]]:
*t(X;18)(p11.2;q11.2).<ref>URL: [http://www.ncbi.nlm.nih.gov/omim/300813 http://www.ncbi.nlm.nih.gov/omim/300813]. Accessed on: 30 May 2010.</ref>
**SYT/SSX fusion gene.
 
Several SSX genes:
*SSX1.
*SSX2 - better survival
*SSX4 - uncommon.
 
Notes:
*At HSC t(X,18) = synovial sarcoma.


=Other=
=Other=
==Granulocytic sarcoma==
==Granulocytic sarcoma==
*Common alternate terms: myeloid sarcoma, chloroma.
*Common alternate terms: extramedullary leukemia,<ref name=pmid21795742>{{Cite journal  | last1 = Bakst | first1 = RL. | last2 = Tallman | first2 = MS. | last3 = Douer | first3 = D. | last4 = Yahalom | first4 = J. | title = How I treat extramedullary acute myeloid leukemia. | journal = Blood | volume = 118 | issue = 14 | pages = 3785-93 | month = Oct | year = 2011 | doi = 10.1182/blood-2011-04-347229 | PMID = 21795742 }}</ref> myeloid sarcoma, chloroma.  
*Other terms:<ref name=pmid21556238>{{Cite journal  | last1 = Eom | first1 = KS. | last2 = Kim | first2 = TY. | title = Intraparenchymal myeloid sarcoma and subsequent spinal myeloid sarcoma for acute myeloblastic leukemia. | journal = J Korean Neurosurg Soc | volume = 49 | issue = 3 | pages = 171-4 | month = Mar | year = 2011 | doi = 10.3340/jkns.2011.49.3.171 | PMID = 21556238 | PMC = 3085814 | url = http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3085814/ }}</ref> myeloblastoma, chloromyeloma, chloromyelosarcoma, granulocytic leukosarcoma, or myelosarcoma.
*Other terms:<ref name=pmid21556238>{{Cite journal  | last1 = Eom | first1 = KS. | last2 = Kim | first2 = TY. | title = Intraparenchymal myeloid sarcoma and subsequent spinal myeloid sarcoma for acute myeloblastic leukemia. | journal = J Korean Neurosurg Soc | volume = 49 | issue = 3 | pages = 171-4 | month = Mar | year = 2011 | doi = 10.3340/jkns.2011.49.3.171 | PMID = 21556238 | PMC = 3085814 | url = http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3085814/ }}</ref> myeloblastoma, chloromyeloma, chloromyelosarcoma, granulocytic leukosarcoma, or myelosarcoma.
 
{{Main|Granulocytic sarcoma}}
===General===
*Soft tissue manifestation of acute myeloid leukemia.<ref name=pmid21556238/>
 
===Microscopic===
Features:
*Cluster of atypical small blue cells in [[soft tissue lesions|soft tissue]].
 
Note:
*May mimic [[small cell carcinoma]], large cell lymphomas ([[DLBCL]], [[ALCL]]), [[small round cell tumour]]s.
 
Images:
*[http://commons.wikimedia.org/wiki/File:Chloroma_-_high_mag.jpg Chloroma - high mag. (WC)].
*[http://commons.wikimedia.org/wiki/File:Chloroma_-_very_high_mag.jpg Chloroma - very high mag. (WC)].


=See also=
=See also=
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