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'''Soft tissue tumours''' 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. 


==WHO classification of soft tissue tumours==
=Introduction=
===Morphologic grouping<ref>WMSP PP.601-3.</ref>===
==WHO classification of soft tissue lesions/tumours==
#Adipocytic tumours.
===Morphologic grouping===
#Fibroblastic/myofibroblastic tumours.
These include:<ref name=Ref_WMSP601-3>{{Ref WMSP|601-3}}</ref>
#"Fibrohistiocytic" tumours.
#[[Adipocytic tumours]].
#Smooth muscle tumours.
#[[Fibroblastic/myofibroblastic tumours]].
#Skeletal muscle tumours.
#[[Fibrohistiocytic tumours|"Fibrohistiocytic" tumours]].
#Vascular tumours.
#[[Smooth muscle tumours|Smooth muscle tumours]].
#Perivascular (pericytic) tumours.
#[[Soft tissue lesions#Skeletal muscle tumours|Skeletal muscle tumours]].
#Chondro-osseous tumours.
#[[Vascular tumours]].
#Tumours of uncertain differentiation.
#[[Soft_tissue_lesions#Perivascular_tumours|Perivascular (pericytic) tumours]].
#[[Chondro-osseous tumours]].
#[[Soft tissue lesions#Tumours of uncertain differentiation|Tumours of uncertain differentiation]].


===Biologic potential grouping<ref>WMSP PP.598-604.</ref>===
===Biologic potential grouping===
These include:<ref>{{Ref WMSP|598-604}}</ref>
#Benign.
#Benign.
#Intermediate (locally aggressive).
#Intermediate (locally aggressive).
Line 19: Line 22:
#Malignant.
#Malignant.


=Other=
==Prevalence==
==Neurofibromatosis==
*All sarcomas are rare buggers. 
Comes in two flavours:
**As the classification has been changing over the past years (with more subtypes being recognized/identified) numbers are variable from study-to-study.
#NF1 (peripheral).
*Once upon a time almost everything was called ''malignant fibrous histiocytoma''; thus, it is listed as a common entity in some publications.
#NF2 (central).


===NF1===
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>
Features (need 2/7 to diagnose):<ref>URL: [http://emedicine.medscape.com/article/1177266-overview http://emedicine.medscape.com/article/1177266-overview]. Accessed on: 3 May 2010.</ref>
*Liposarcoma.
*Two or more neurofibromas or one plexiform neurofibroma.
*Leiomyosarcoma.
*Café-au-lait spots.
*Freckles in axilla or inguinal area.
*Optic nerve glioma.
*Iris hamartomas (Lisch nodules).
*Sphenoid dysplasia or typical long-bone abnormalities (e.g. bowing).
*First-degree relative with NF1.


===NF2===
==Molecular testing==
Features (need 1/3 to diagnose):<ref>URL: [http://emedicine.medscape.com/article/1178283-overview http://emedicine.medscape.com/article/1178283-overview]. Accessed on: 3 May 2010.</ref>
{{Main|Molecular pathology}}
#Bilateral CNVIII masses on imaging.
*Molecular testing plays an important role in soft tissue pathology.
#Unilateral CNVIII mass + first-degree relative with NF2.
*It is generally seen as an adjunct test that:<ref name=pmid11454050>{{cite journal |author=Fletcher CD, Fletcher JA, Dal Cin P, Ladanyi M, Woodruff JM |title=Diagnostic gold standard for soft tissue tumours: morphology or molecular genetics? |journal=Histopathology |volume=39 |issue=1 |pages=100–3 |year=2001 |month=July |pmid=11454050 |doi= |url=}}</ref>
#First-degree relative with NF2 ''and'' 2/4 of the following:   
**Often is used to confirm the histomorphologic impression/quality control.
## Meningioma.
**Frequently has some prognostic significance.
## Glioma.
**May directly affect treatment.
## Schwannoma.
## Juvenile cataract.


==Small round blue cell tumours (SRBCT)==
===Translocations===
A group of tumours that has a similar histologic appearance.  It is a group of tumours that is seen more often in childhood than adulthood.
{{Main|Chromosomal translocations}}
*Many tumours in soft tissue pathology are diagnosed inconjunction with the finding of [[chromosomal translocations]].


===DDx===
==Morphohistologic patterns==
*Neuroblastoma.
{{Main|Morphologic patterns}}
*Wilm's tumour.
{| class="wikitable sortable" style="margin-left:auto;margin-right:auto"
*Alveolar rhabdomyosarcoma.
! Name
*Ewing sarcoma/PNET - this entity is dealt with in the ''[[bone]]'' article.
! Description
*Lymphoma (diffuse large B cell lymphoma).
! DDx
*Retinoblastoma.
! Image(s)
*Hepatoblastoma.
|-
*Desmoplastic small round cell tumour.
| 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
| [[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>
| [[Image:Storiform_pattern_-_intermed_mag.jpg |thumb|center|150px| Patternless pattern. (WC)]]
|-
| 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
| [[fibrosarcoma]], [[synovial sarcoma]], [[MPNST]]
| [[Image:Malignant_peripheral_nerve_sheath_tumour_-_intermed_mag.jpg |thumb|center|150px |Herring bone. (WC)]]  
|-
| Fascicular
| the long axis of the (spindle) cells are perpendicular to one another in adjacent bundles of cells
| [[leiomyoma]], [[leiomyosarcoma]]
| [[Image:Cutaneous_leiomyosarcoma_-_high_mag.jpg |thumb|center|150px| Fascicular pattern. (WC)]]
|-
| Biphasic
| nests of cells and stroma
| [[synovial sarcoma]], [[DSRCT]], [[alveolar RMS]]
| [[Image:Desmoplastic_small_round_cell_tumour_-_high_mag.jpg|thumb|center|150px| DSRCT. (WC)]]
|- <!--
| name ?
| description ?
| DDx ?
| image ? -->
|}


===Microscopic===
Notes:
Features:
*Memory device: herring bone DDx ''MSF'' = MPNST, Synovial sarcoma, Fibrosarcoma.
*Sheets of cells, very cellular.
*Small cells ~ 2X RBC diameter.
*Scant cytoplasm.
*Coarse chromatin.
*Nucleolus (???).
*+/-Vascular.


=Adipocytic tumours=
==Grading==
==Hibernoma==
*Several systems exist.
===General===
*The US-CAP advocates the use of the French system over the NCI system.
*Consists of ''brown fat'' (present in the infants to generate heat).<ref>WMSP P.605.</ref>
**The French system is a better predictor metastases and mortality.<ref name=pmid8996162>{{cite journal |author=Guillou L, Coindre JM, Bonichon F, ''et al.'' |title=Comparative study of the National Cancer Institute and French Federation of Cancer Centers Sarcoma Group grading systems in a population of 410 adult patients with soft tissue sarcoma |journal=J. Clin. Oncol. |volume=15 |issue=1 |pages=350–62 |year=1997 |month=January |pmid=8996162 |doi= |url=}}</ref>
*Benign.
*Usually asymptomatic.<ref name=pmid19131775>{{cite journal |author=Ahmed SA, Schuller I |title=Pediatric hibernoma: a case review |journal=J. Pediatr. Hematol. Oncol. |volume=30 |issue=12 |pages=900–1 |year=2008 |month=December |pmid=19131775 |doi=10.1097/MPH.0b013e318184e6dd |url=}}</ref>


===Epidemiology===
===French system===
*Young adults.
*Formally known as the grading system from the ''French Federation of Cancer Centres Sarcoma Group'' (FNCLCC).


===Gross===
====Overview====
*Well-circumscribed.
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>
*Lobulated and light-brown on sectioning.
#Differentiation (score 1-3).
#*De facto, this is mostly the ''histologic type''.
#Mitotic rate (score 1-3).
#Necrosis (score 0-2)


===Microscopic===
Obtaining a score:
Features:<ref>{{cite journal |author=Chen DY, Wang CM, Chan HL |title=Hibernoma. Case report and literature review |journal=Dermatol Surg |volume=24 |issue=3 |pages=393–5 |year=1998 |month=March |pmid=9537018 |doi= |url=}}</ref>
*Add all the points from the three components.
*Large polygonal/oval cells:
**Nucleus - central & small.<ref>[http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675(06)70271-6 http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675(06)70271-6]</ref>
***Nucleoli typically prominent.<ref>[http://surgpathcriteria.stanford.edu/softfat/hibernoma/ http://surgpathcriteria.stanford.edu/softfat/hibernoma/]</ref>
**Cytoplasm - multivacuolated, oval, eosinophilic, granular.


Image:
Scoring:
*[http://en.wikipedia.org/wiki/File:Hibernoma1.jpg Hibernoma (WC)].
*Grade 1 = 2-3.
*Grade 2 = 4-5.
*Grade 3 = 6-8.


==Liposarcoma==
=====Differentiation=====
*Most common malignant sarcoma in the retroperitoneum.
*Standardized for histologic types.
*Most tumours = 3/3.


===Microscopy===
Exceptions:<ref name=uscap_stp/>
Features:
*Well-differentiated liposarcoma = 1.
*Lipoblasts:
*Myxoid liposarcoma = 2.
**Large sharply demarcated vacuole.
*Conventional [[liposarcoma]] = 2.
**Nucleus:
*Fibrosarcoma = 2.
***Hyperchromatic (dark staining) nucleus.
*[[Myxofibrosarcoma]] =2.
***Eccentric location.
***Nuclear indentation.


Images:
A group of tumours is not graded:<ref name=uscap_stp/>
*[http://commons.wikimedia.org/wiki/File:Myxoid_liposarcoma_%2806%29.JPG Myxoid liposarcoma (WC)].
*[[MPNST]].
*[http://commons.wikimedia.org/wiki/File:Myxoid_liposarcoma_%2805%29.JPG Myxoid liposarcoma (WC)].
*[[Rhabdomyosarcoma]].
*[http://www.john-libbey-eurotext.fr/e-docs/00/04/09/14/texte_alt_jleejd00046_gr5.jpg Lipoblasts (john-libbey-eurotext.fr)].
*[[Alveolar soft part sarcoma]].
*[[Clear cell sarcoma]].
*[[Extraskeletal myxoid chondrosarcoma]].


===IHC===
=====Mitotic rate=====
*IHC is of limited value.
*0-9 mitoses/10 HPF.
*10-19 mitoses/10 HPF.
*>=20 mitoses/10 HPF.


*S-100 +ve ~1/3 of the time.
Notes:
*Reticulin ???.
*1 HPF = 0.1734 mm^2.
**Most resident microscopes have a field of view = 0.2376 mm^2.
***Thus, ~7.3 HPFs on a resident microscope corresponds to 10 US-CAP HPFs.


=Smooth muscle tumours=
=====Necrosis=====
==Leiomyosarcoma==
*None = score 0.
See gyne notes.
*<=50% of tumour = score 1.
*>50% of tumour = score 2.


===Microscopy===
===System used by some at MSH===
Features:
Some pathologists at [[MSH]] use the system advocated by Costa et al..<ref name=pmid6692258>{{cite journal |author=Costa J, Wesley RA, Glatstein E, Rosenberg SA |title=The grading of soft tissue sarcomas. Results of a clinicohistopathologic correlation in a series of 163 cases |journal=Cancer |volume=53 |issue=3 |pages=530–41 |year=1984 |month=February |pmid=6692258 |doi= |url=}}</ref>
*Nuclear atypia.
*Necrosis.
*Mitoses.


=Fibroblastic/myofibroblastic tumours=
====Scoring====
*Grade 1 = 1 point.
*Grade 2 = 2 points.
*Grade 3 = 3-4 points.


==Proliferative fasciitis==
====Components====
*Need to write something here.
Points for each of the following:
*Mitotic activity >= 6 / 10 HPF @ 40X - definition suffers from [[HPFitis]].
*Pleomorphism present.
*Cellularity (cells/matrix) > 50%.
*Necrosis >15% - microscopic (without targeting necrosis grossly) ''or'' grossly.


==Hemangiopericytoma==
==Stage==
===General===
{{Main|Cancer staging systems}}
*Grouped with ''solitary fibrous tumour'' in the WHO classification; possibly the same tumour (?).<ref>WMSP P.609.</ref>
===Lymph node metastases in sarcomas===
*Arises from the ''pericyte'', a connective tissue cell of small vessels that is thought to be involved in flow regulation.
{{Main|Lymph node metastasis}}
*Hematologic spread most common - to lungs.<ref>URL: [http://emedicine.medscape.com/article/1255879-overview http://emedicine.medscape.com/article/1255879-overview]. Accessed on: 2 May 2010.</ref>
*[[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>
*Oncogenic osteomalacia - assoc. with hemangiopericytoma.<ref>URL: [http://emedicine.medscape.com/article/1255879-overview http://emedicine.medscape.com/article/1255879-overview]. Accessed on: 2 May 2010.</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.


===Presentation===
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>
*Usually painless mass, slow enlargement.
*[[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]].


====Radiology====
==DDx by history/site==
*Intramedullary lytic mass.
===Retroperiteum===
*May be well-circumscribed.
#[[Liposarcoma]].
*+/-Periosteal reaction.
#[[Undifferentiated pleomorphic sarcoma]].
*+/-Sclerotic border.
#[[Leiomyosarcoma]].
#[[MPNST]].


May be worked-up with angiography to distinguish from a vascular malformation.<ref>URL: [http://emedicine.medscape.com/article/1255879-diagnosis http://emedicine.medscape.com/article/1255879-diagnosis]. Accessed on: 2 May 2010.</ref>
Note:
===Location===
[[Synovial sarcoma]] and [[fibrosarcoma]] are very rare in the retroperitoneum.
*Usually extremities - femur or prox. tibial.<ref>URL: [http://emedicine.medscape.com/article/1255879-overview http://emedicine.medscape.com/article/1255879-overview]. Accessed on: 2 May 2010.</ref>


===Histology===
===Young person - extremity sarcoma===
Features:<ref>URL: [http://emedicine.medscape.com/article/1255879-diagnosis http://emedicine.medscape.com/article/1255879-diagnosis]. Accessed on: 2 May 2010.</ref>
#[[Epithelioid sarcoma]].
*Hypervascular lesion - '''key diagnostic feature'''.<ref name=enzinger>Enzinger & Weiss's Soft Tissue Tumors. 4th Ed. PP.1007-13. ISBN 0-323-01200-0.</ref>
#[[Synovial sarcoma]].
**Abundant thin-walled branching small vessels of variable size.
***May be described as "staghorn vessels" or "antler-like" vasculature.
***Cells may "onion-skin" around thin blood vessels.
*Spindle or ovoid shaped cells in nests or sheets.


===IHC===
==Gross characteristics==
Features:<ref>WMSP P.609.</ref><ref name=enzinger/>
*Usually non-specific.
*Vimentin +ve (usually).
*Most sarcomas have a pushing border.
*Desmin -ve (typical).
**If there is an infiltrative border think: (1) fibromatosis, (2) carcinoma.
*Factor VIII -ve (marks endothelium).
*CD34 +ve.
**CD34 usu. -ve in synovial sarcoma.
*CD31 -ve (marks benign endothelium).
*vWF (von Willebrand factor) -ve.


===DDx===
=Adipocytic tumours=
*Other vascular tumours.
{{Main|Adipocytic tumours}}
*Vascular malformations.
*Synovial sarcoma.


==Desmoplastic fibroblastoma==
This category includes:
*AKA ''collagenous fibroma''.<ref name=pmid18271804>PMID 18271804.</ref>
*Lipoma.
*Benign lesion.
*Liposarcoma.
*Classically found in shoulder region.
*Hibernoma.


===IHC===
=Smooth muscle tumours=
*Beta-catenin -ve.<ref name=pmid18544056>PMID 18544056.</ref>
{{Main|Smooth muscle tumours}}
**Significance ???
IHC markers: desmin, SMA, H-caldemsin (most specific).


=Vascular tumours=
==Leiomyosarcoma==
==Kaposi sarcoma==
{{Main|Leiomyosarcoma}}
===General===
*Not really a sarcoma.
*Caused by HHV-8.
*Associated with immunodeficiency, e.g. HIV/AIDS.


===Stages===
===Microscopic===
It is seen in different stages:<ref>URL: [http://www.histopathology-india.net/KS.htm http://www.histopathology-india.net/KS.htm]. Accessed on: 31 January 2010.</ref>
Features (summary):
#Patch stage.
*Fasicular cellular spindle cell lesion with:
#Plaque stage.
**Nuclear atypia.
#Nodular stage.
**[[Necrosis]].
#Lymphangioma-like. (???)
**High mitotic rate.


===Microscopic===
=Fibrohistiocytic tumours=
Features:<ref>Klatt. AOP P.23.</ref>
''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>
*Vascular channels that anastomose.
*+/-Nuclear atypia.
*Hyaline globules - pale pink globs (that are paler than RBCs) - '''key feature'''.
*+/-Hemosiderin deposits.


DDx:
==Pleomorphic undifferentiated sarcoma==
*Angiosarcoma (have many mitoses).
*Abbreviated ''PUS''.
*[[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>
{{Main|Pleomorphic undifferentiated sarcoma}}


===IHC===
=Fibroblastic/myofibroblastic tumours=
*CD31 +ve, CD34 +ve, HHV-8 +ve.
{{Main|Fibroblastic/myofibroblastic tumours}}


==Angiosarcoma==
This is a very large and important group of soft tissue lesions.  It is covered in a separate article.
*Malignant tumour.


===Microscopic===
The grouping includes:
Features:
*[[Inflammatory myofibroblastic tumour]].
*Very many small capillaries or irregular shape lined with:
*[[Nodular fasciitis]].
**Atypical nuclei, pleomorphic nuclei.
*[[Desmoid-type fibromatosis]] (Desmoid tumour).
*Mitoses.
*[[Proliferative fasciitis]].
*Cytoplasmic vacuoles.
*[[Solitary fibrous tumour]] ([[Hemangiopericytoma]]).
**Cells trying to form lumina - embryologic.
*[[Desmoplastic fibroblastoma]].
*[[Low-grade fibromyxoid sarcoma]].
*Others.


==Hemangioendothelioma==
=Perivascular tumours=
*Usually benign.
This grouping includes only two:<ref name=Ref_WMSP602>{{Ref WMSP|602}}</ref>
*[[Glomus tumour]] - both benign and malignant.
*[[Myopericytoma]].


===Microscopic===
=Vascular lesions=
Features:<ref>Klatt. AOP P.23.</ref>
{{Main|Vascular lesions}}
*Well-formed thin vascular channels on a fibrous stroma - '''key feature'''.
Vascular lesions are "too red"; they have too many RBCs.
*+/-Thrombosis.
*+/-Calcification.
*+/-Fibrosis.
*+/-Myxoid change.


===IHC===
They include:
*Factor VIII +ve.
*[[Hemangioma]].
*[[Kaposi sarcoma]].
*[[Masson hemangioma]].
*[[Angiosarcoma]]
*[[Epithelioid hemangioendothelioma]].


=Skeletal muscle tumours=
=Skeletal muscle tumours=
==Rhabdomyoma==
{{Main|Rhabdomyoma}}
==Rhabdomyosarcoma==
==Rhabdomyosarcoma==
*Often abbreviated ''RMS''.
*Abbreviated ''RMS''.
*Most common paediatric sarcoma.
*~6% of all childhood cancer.


Histological subdivision:
{{Main|Rhabdomyosarcoma}}
#Alveolar rhabdomyosarcoma.
Comes it two main flavours:
#*Usually young adults/adolescents.
*Alveolar rhabdomyosarcoma.
#*Early mets common.
*Embryonal rhabdomyosarcoma.
#Embryonal rhabdomyosarcoma.
#*Usual <10 years old.
#*Typically locally invasive.
 
Molecular and histologic subdivision:
#Translocation-positive alveolar RMS.
#Translocation-negative alveolar RMS.
#Embryonal RMS.
 
Notes:
*Translocation-negative alveolar RMS shares characteristics with ''embryonal RMS''.


===Microscopy===
The histology may be that of a [[small round cell tumour]].
Alveolar rhabdomyosarcoma:
*Alveolus-like pattern:
**Fibrous septae lined by tumour cells.
***Space between fibrous sepate may be filled with tumour: ''solid variant of alveolar rhabdomyosarcoma''.
*Eccentric nucleus (???).
*Cytoplasm - dense pink staining on H&E (if well differentiated).
*Usu. nuclear pleomorphism +++.
*Mitoses common.


===Molecular diagnostics===
=Chondro-osseous tumours=
====Alveolar rhabdomyosarcoma====
{{Main|Chondro-osseous tumours}}
Common translocations (~80%):
*t(1,13).
**PAX3/FKHR fusion gene.
*t(2,13).
**PAX7/FKHR fusion gene.


Several uncommon translocations exist.
This grouping includes tumours derived from [[cartilage]] and [[bone]].
 
===IHC===
*Desmin (best marker).
*Actin.


=Tumours of uncertain differentiation=
=Tumours of uncertain differentiation=
==Clear cell sarcoma==
==Angiomatoid fibrous histiocytoma==
*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|Angiomatoid fibrous histiocytoma}}
**Molecular changes and origin distinct from melanoma.
*Incidence: rare soft tissue tumour.


===Clinical===
==Aggressive angiomyxoma==
*Usually - deep soft tissue ''or'' extremities.
*[[AKA]] deep aggressive angiomyxoma.
*Guarded prognosis.
{{Main|Aggressive angiomyxoma}}
*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===
==Angiomyofibroblastoma==
Features:<ref name=pmid18300804/>
{{Main|Angiomyofibroblastoma}}
*Architecture: sheets or fascicular (bundles) arrangement.
*Cells: Spindle cells or epithelioid cells.
*Prominent nucleoli - basophilic.
*Fibrous septae.
*Uniform


Image:
==Extrarenal malignant rhabdoid tumour==
*[http://commons.wikimedia.org/wiki/File:Clear_cell_sarcoma.Image12.jpg Clear cell sarcoma (WC)].
*Essentially identical to ''[[renal malignant rhabdoid tumour]]''.<ref name=Ref_WMSP627>{{Ref WMSP|627}}</ref>
*[http://www.informaworld.com/ampp/image?path=/713690780/789166263/sonc_a_284443_o_f0003g.jpeg Clear cell sarcoma (informaworld.com)].
{{Main|Extrarenal malignant rhabdoid tumour}}


===IHC===
==Ewing sarcoma/PNET==
Features:<ref name=pmid18300804/>
{{Main|Ewing sarcoma}}
*S100 +ve.
*A [[small round blue cell tumour]] that may be seen in [[bone]]. It is discussed in the context of [[bone tumours]].
*HMB-45 +ve.
*Melan A (MART-1) +ve; sometimes -ve.
*bcl-2 +ve.
*CD57 +ve (usually).


Keratins:
==Epithelioid sarcoma==
*EMA may be +ve.
:Sarcomas with an epithelioid morphology are covered in ''[[epithelioid sarcomas]]''.
*CAM5.2 -ve.
{{Main|Epithelioid sarcoma}}
*AE1/AE3 -ve.


===Molecular studies===
==Alveolar soft part sarcoma==
*Chromosomal translocation t(12;22)(q13;q12).<ref name=pmid18300804/>
{{Main|Alveolar soft part sarcoma}}
**Fusion transcripts:
***EWSR1-ATF1.
***EWSR1-CREB1 (GI tract associated).


==Chondrosarcoma==
==Desmoplastic small round cell tumour==
*May arise from an ''enchondroma''.
{{Main|Desmoplastic small round cell tumour}}
*Usually a good prognosis.


==Clear cell sarcoma==
{{Main|Clear cell sarcoma}}


==Synovial sarcoma==
{{Main|Synovial sarcoma}}


===Microscopic===
=Other=
Features:
==Granulocytic sarcoma==
*Resembles cartilage at low power.<ref>Klatt. AOP P.417.</ref>
*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.
*More cellular than cartilage... but relatively paucicellular compared to other sarcomas.
*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}}
Images:
*[http://commons.wikimedia.org/wiki/File:Chondrosarcoma_(1).jpg Chondrosarcoma - low mag. (WC)].
*[http://commons.wikimedia.org/wiki/File:Chondrosarcoma_(2).jpg Chondrosarcoma - high mag. (WC)].
*[http://commons.wikimedia.org/wiki/File:Chondrosarcoma_(3).jpg Chondrosarcoma - high mag. (WC)].
 
====Grading====
Features:<ref>WMSP P.643.</ref>
*Grade I: moderate cellularity +/- binucleated cells.
*Grade III: nuclear pleomorphism, mitoses common.
*Grade II: between Grade I and Grade III.


=See also=
=See also=
Line 348: Line 315:
*[[Hematopathology]].
*[[Hematopathology]].
*[[Spindle cell lesion]].
*[[Spindle cell lesion]].
*[[Neurofibromatosis]].
*[[Small round cell tumours]].


=References=
=References=
{{reflist|2}}
{{reflist|2}}


[[Category:Weird stuff]]
[[Category:Soft tissue lesions]]
Michael
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