Difference between revisions of "Soft tissue lesions"

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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.


=Adipocytic tumours=
==Prevalence==
==Liposarcoma==
*All sarcomas are rare buggers. 
*Most common malignant sarcoma in the retroperitoneum.
**As the classification has been changing over the past years (with more subtypes being recognized/identified) numbers are variable from study-to-study.
*Once upon a time almost everything was called ''malignant fibrous histiocytoma''; thus, it is listed as a common entity in some publications.


===Microscopy===
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:
*Liposarcoma.
*Lipoblasts:
*Leiomyosarcoma.
**Large sharply demarcated vacuole.
**Nucleus:
***Hyperchromatic (dark staining) nucleus.
***Eccentric location.
***Nuclear indentation.


Images:
==Molecular testing==
*[http://commons.wikimedia.org/wiki/File:Myxoid_liposarcoma_%2806%29.JPG Myxoid liposarcoma (WC)].
{{Main|Molecular pathology}}
*[http://commons.wikimedia.org/wiki/File:Myxoid_liposarcoma_%2805%29.JPG Myxoid liposarcoma (WC)].
*Molecular testing plays an important role in soft tissue pathology.
*[http://www.john-libbey-eurotext.fr/e-docs/00/04/09/14/texte_alt_jleejd00046_gr5.jpg Lipoblasts (john-libbey-eurotext.fr)].
*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>
**Often is used to confirm the histomorphologic impression/quality control.
**Frequently has some prognostic significance.
**May directly affect treatment.


===IHC===
===Translocations===
*IHC is of limited value.
{{Main|Chromosomal translocations}}
*Many tumours in soft tissue pathology are diagnosed inconjunction with the finding of [[chromosomal translocations]].


*S-100 +ve ~1/3 of the time.
==Morphohistologic patterns==
*Reticulin ???.
{{Main|Morphologic patterns}}
{| class="wikitable sortable" style="margin-left:auto;margin-right:auto"
! Name
! Description
! DDx
! Image(s)
|-
| 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 ? -->
|}


=Smooth muscle tumours=
Notes:
==Leiomyosarcoma==
*Memory device: herring bone DDx ''MSF'' = MPNST, Synovial sarcoma, Fibrosarcoma.
See gyne notes.


===Microscopy===
==Grading==
Features:
*Several systems exist.
*Nuclear atypia.
*The US-CAP advocates the use of the French system over the NCI system.
*Necrosis.
**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>
*Mitoses.


=Fibroblastic/myofibroblastic tumours=
===French system===
*Formally known as the grading system from the ''French Federation of Cancer Centres Sarcoma Group'' (FNCLCC).


==Proliferative fasciitis==
====Overview====
*Need to write something here.
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).
#*De facto, this is mostly the ''histologic type''.
#Mitotic rate (score 1-3).
#Necrosis (score 0-2)


==Hemangiopericytoma==
Obtaining a score:
===General===
*Add all the points from the three components.
*Grouped with ''solitary fibrous tumour'' in the WHO classification; possibly the same tumour (?).<ref>WMSP P.609.</ref>
*Arises from the ''pericyte'', a connective tissue cell of small vessels that is thought to be involved in flow regulation.
*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>
*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>


===Presentation===
Scoring:
*Usually painless mass, slow enlargement.
*Grade 1 = 2-3.
*Grade 2 = 4-5.
*Grade 3 = 6-8.


====Radiology====
=====Differentiation=====
*Intramedullary lytic mass.
*Standardized for histologic types.
*May be well-circumscribed.
*Most tumours = 3/3.
*+/-Periosteal reaction.
*+/-Sclerotic border.


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>
Exceptions:<ref name=uscap_stp/>
===Location===
*Well-differentiated liposarcoma = 1.
*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>
*Myxoid liposarcoma = 2.
*Conventional [[liposarcoma]] = 2.
*Fibrosarcoma = 2.
*[[Myxofibrosarcoma]] =2.


===Histology===
A group of tumours is not graded:<ref name=uscap_stp/>
Features:<ref>URL: [http://emedicine.medscape.com/article/1255879-diagnosis http://emedicine.medscape.com/article/1255879-diagnosis]. Accessed on: 2 May 2010.</ref>
*[[MPNST]].
*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>
*[[Rhabdomyosarcoma]].
**Abundant thin-walled branching small vessels of variable size.
*[[Alveolar soft part sarcoma]].
***May be described as "staghorn vessels" or "antler-like" vasculature.
*[[Clear cell sarcoma]].
***Cells may "onion-skin" around thin blood vessels.
*[[Extraskeletal myxoid chondrosarcoma]].
*Spindle or ovoid shaped cells in nests or sheets.


===IHC===
=====Mitotic rate=====
Features:<ref>WMSP P.609.</ref><ref name=enzinger/>
*0-9 mitoses/10 HPF.
*Vimentin +ve (usually).
*10-19 mitoses/10 HPF.
*Desmin -ve (typical).
*>=20 mitoses/10 HPF.
*Factor VIII -ve (marks endothelium).
*CD34 +ve.
**CD34 usu. -ve in synovial sarcoma.
*CD31 -ve (marks benign endothelium).
*vWF (von Willebrand factor) -ve.


===DDx===
Notes:
*Other vascular tumours.
*1 HPF = 0.1734 mm^2.
*Vascular malformations.
**Most resident microscopes have a field of view = 0.2376 mm^2.
*Synovial sarcoma.
***Thus, ~7.3 HPFs on a resident microscope corresponds to 10 US-CAP HPFs.


==Desmoplastic fibroblastoma==
=====Necrosis=====
*AKA ''collagenous fibroma''.<ref name=pmid18271804>PMID 18271804.</ref>
*None = score 0.
*Benign lesion.
*<=50% of tumour = score 1.
*Classically found in shoulder region.
*>50% of tumour = score 2.


===IHC===
===System used by some at MSH===
*Beta-catenin -ve.<ref name=pmid18544056>PMID 18544056.</ref>
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>
**Significance ???


=Vascular tumours=
====Scoring====
==Hemangioendothelioma==
*Grade 1 = 1 point.
*Usually benign.
*Grade 2 = 2 points.
*Grade 3 = 3-4 points.


===Microscopic===
====Components====
Features:<ref>Klatt. AOP P.23.</ref>
Points for each of the following:
*Well-formed thin vascular channels on a fibrous stroma - '''key feature'''.
*Mitotic activity >= 6 / 10 HPF @ 40X - definition suffers from [[HPFitis]].
*+/-Thrombosis.
*Pleomorphism present.
*+/-Calcification.
*Cellularity (cells/matrix) > 50%.
*+/-Fibrosis.
*Necrosis >15% - microscopic (without targeting necrosis grossly) ''or'' grossly.
*+/-Myxoid change.


===IHC===
==Stage==
*Factor VIII +ve.
{{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.


==Neurofibromatosis==
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>
Comes in two flavours:
*[[rhabdomyosarcoma|'''R'''habdomyosarcoma]]
#NF1 (peripheral).
*[[Angiosarcoma|'''A'''ngiosarcoma]].
#NF2 (central).
*[[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]].


===NF1===
==DDx by history/site==
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>
===Retroperiteum===
*Two or more neurofibromas or one plexiform neurofibroma.
#[[Liposarcoma]].
*Café-au-lait spots.
#[[Undifferentiated pleomorphic sarcoma]].
*Freckles in axilla or inguinal area.
#[[Leiomyosarcoma]].
*Optic nerve glioma.
#[[MPNST]].
*Iris hamartomas (Lisch nodules).
*Sphenoid dysplasia or typical long-bone abnormalities (e.g. bowing).
*First-degree relative with NF1.


===NF2===
Note:
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>
[[Synovial sarcoma]] and [[fibrosarcoma]] are very rare in the retroperitoneum.
#Bilateral CNVIII masses on imaging.
#Unilateral CNVIII mass + first-degree relative with NF2.
#First-degree relative with NF2 ''and'' 2/4 of the following:   
## Meningioma.
## Glioma.
## Schwannoma.
## Juvenile cataract.


===Young person - extremity sarcoma===
#[[Epithelioid sarcoma]].
#[[Synovial sarcoma]].


==Hibernoma==
==Gross characteristics==
===General===
*Usually non-specific.
*Consists of ''brown fat'' (present in the infants to generate heat).<ref>WMSP P.605.</ref>
*Most sarcomas have a pushing border.
*Benign.
**If there is an infiltrative border think: (1) fibromatosis, (2) carcinoma.
*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===
=Adipocytic tumours=
*Young adults.
{{Main|Adipocytic tumours}}


===Gross===
This category includes:
*Well-circumscribed.
*Lipoma.
*Lobulated and light-brown on sectioning.
*Liposarcoma.
*Hibernoma.


===Microscopic===
=Smooth muscle tumours=
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>
{{Main|Smooth muscle tumours}}
*Large polygonal/oval cells:
IHC markers: desmin, SMA, H-caldemsin (most specific).
**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:
==Leiomyosarcoma==
*[http://en.wikipedia.org/wiki/File:Hibernoma1.jpg Hibernoma (WC)].
{{Main|Leiomyosarcoma}}


==Small round blue cell tumours (SRBCT)==
===Microscopic===
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.
Features (summary):
*Fasicular cellular spindle cell lesion with:
**Nuclear atypia.
**[[Necrosis]].
**High mitotic rate.


===DDx===
=Fibrohistiocytic tumours=
*Neuroblastoma.
''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>
*Wilm's tumour.
*Alveolar rhabdomyosarcoma.
*Ewing sarcoma/PNET - this entity is dealt with in the ''[[bone]]'' article.
*Lymphoma (diffuse large B cell lymphoma).
*Retinoblastoma.
*Hepatoblastoma.
*Desmoplastic small round cell tumour.


===Microscopic===
==Pleomorphic undifferentiated sarcoma==
Features:
*Abbreviated ''PUS''.
*Sheets of cells, very cellular.
*[[AKA]] ''Undifferentiated pleomorphic sarcoma'', abbreviated ''UPS''.
*Small cells ~ 2X RBC diameter.
*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>
*Scant cytoplasm.
{{Main|Pleomorphic undifferentiated sarcoma}}
*Coarse chromatin.
*Nucleolus (???).
*+/-Vascular.


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


===Stages===
This is a very large and important group of soft tissue lesions.  It is covered in a separate article.
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>
#Patch stage.
#Plaque stage.
#Nodular stage.
#Lymphangioma-like. (???)


===Microscopic===
The grouping includes:
Features:<ref>Klatt. AOP P.23.</ref>
*[[Inflammatory myofibroblastic tumour]].
*Vascular channels that anastomose.
*[[Nodular fasciitis]].
*+/-Nuclear atypia.
*[[Desmoid-type fibromatosis]] (Desmoid tumour).
*Hyaline globules - pale pink globs (that are paler than RBCs) - '''key feature'''.
*[[Proliferative fasciitis]].
*+/-Hemosiderin deposits.
*[[Solitary fibrous tumour]] ([[Hemangiopericytoma]]).
*[[Desmoplastic fibroblastoma]].
*[[Low-grade fibromyxoid sarcoma]].
*Others.


DDx:
=Perivascular tumours=
*Angiosarcoma (have many mitoses).
This grouping includes only two:<ref name=Ref_WMSP602>{{Ref WMSP|602}}</ref>
*[[Glomus tumour]] - both benign and malignant.
*[[Myopericytoma]].


===IHC===
=Vascular lesions=
*CD31 +ve, CD34 +ve, HHV-8 +ve.
{{Main|Vascular lesions}}
Vascular lesions are "too red"; they have too many RBCs.


==Angiosarcoma==
They include:
*Malignant tumour.
*[[Hemangioma]].
*[[Kaposi sarcoma]].
*[[Masson hemangioma]].
*[[Angiosarcoma]]
*[[Epithelioid hemangioendothelioma]].


===Microscopic===
=Skeletal muscle tumours=
Features:
==Rhabdomyoma==
*Very many small capillaries or irregular shape lined with:
{{Main|Rhabdomyoma}}
**Atypical nuclei, pleomorphic nuclei.
*Mitoses.
*Cytoplasmic vacuoles.
**Cells trying to form lumina - embryologic.


==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:
The histology may be that of a [[small round cell tumour]].
#Translocation-positive alveolar RMS.
#Translocation-negative alveolar RMS.
#Embryonal RMS.


Notes:
=Chondro-osseous tumours=
*Translocation-negative alveolar RMS shares characteristics with ''embryonal RMS''.
{{Main|Chondro-osseous tumours}}
 
This grouping includes tumours derived from [[cartilage]] and [[bone]].


===Microscopy===
=Tumours of uncertain differentiation=
Alveolar rhabdomyosarcoma:
==Angiomatoid fibrous histiocytoma==
*Alveolus-like pattern:
{{Main|Angiomatoid fibrous histiocytoma}}
**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===
==Aggressive angiomyxoma==
====Alveolar rhabdomyosarcoma====
*[[AKA]] deep aggressive angiomyxoma.
Common translocations (~80%):
{{Main|Aggressive angiomyxoma}}
*t(1,13).
**PAX3/FKHR fusion gene.
*t(2,13).
**PAX7/FKHR fusion gene.


Several uncommon translocations exist.
==Angiomyofibroblastoma==
{{Main|Angiomyofibroblastoma}}


===IHC===
==Extrarenal malignant rhabdoid tumour==
*Desmin (best marker).
*Essentially identical to ''[[renal malignant rhabdoid tumour]]''.<ref name=Ref_WMSP627>{{Ref WMSP|627}}</ref>
*Actin.
{{Main|Extrarenal malignant rhabdoid tumour}}


==Clear cell sarcoma==
==Ewing sarcoma/PNET==
*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|Ewing sarcoma}}
**Molecular changes and origin distinct from melanoma.  
*A [[small round blue cell tumour]] that may be seen in [[bone]]. It is discussed in the context of [[bone tumours]].
*Incidence: rare soft tissue tumour.


===Clinical===
==Epithelioid sarcoma==
*Usually - deep soft tissue ''or'' extremities.
:Sarcomas with an epithelioid morphology are covered in ''[[epithelioid sarcomas]]''.
*Guarded prognosis.
{{Main|Epithelioid sarcoma}}
*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===
==Alveolar soft part sarcoma==
Features:<ref name=pmid18300804/>
{{Main|Alveolar soft part sarcoma}}
*Architecture: sheets or fascicular (bundles) arrangement.
*Cells: Spindle cells or epithelioid cells.
*Prominent nucleoli - basophilic.
*Fibrous septae.
*Uniform


Image:
==Desmoplastic small round cell tumour==
*[http://commons.wikimedia.org/wiki/File:Clear_cell_sarcoma.Image12.jpg Clear cell sarcoma (WC)].
{{Main|Desmoplastic small round cell tumour}}
*[http://www.informaworld.com/ampp/image?path=/713690780/789166263/sonc_a_284443_o_f0003g.jpeg Clear cell sarcoma (informaworld.com)].


===IHC===
==Clear cell sarcoma==
Features:<ref name=pmid18300804/>
{{Main|Clear cell sarcoma}}
*S100 +ve.
*HMB-45 +ve.
*Melan A (MART-1) +ve; sometimes -ve.
*bcl-2 +ve.
*CD57 +ve (usually).


Keratins:
==Synovial sarcoma==
*EMA may be +ve.
{{Main|Synovial sarcoma}}
*CAM5.2 -ve.
*AE1/AE3 -ve.


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


==See also==
=See also=
*[[Bone]].
*[[Bone]].
*[[Dermatopathology]].
*[[Dermatopathology]].
*[[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]]

Latest revision as of 12:50, 3 November 2015

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

Introduction

WHO classification of soft tissue lesions/tumours

Morphologic grouping

These include:[1]

  1. Adipocytic tumours.
  2. Fibroblastic/myofibroblastic tumours.
  3. "Fibrohistiocytic" tumours.
  4. Smooth muscle tumours.
  5. Skeletal muscle tumours.
  6. Vascular tumours.
  7. Perivascular (pericytic) tumours.
  8. Chondro-osseous tumours.
  9. Tumours of uncertain differentiation.

Biologic potential grouping

These include:[2]

  1. Benign.
  2. Intermediate (locally aggressive).
  3. Intermediate (rarely metastasizing).
  4. Malignant.

Prevalence

  • All sarcomas are rare buggers.
    • As the classification has been changing over the past years (with more subtypes being recognized/identified) numbers are variable from study-to-study.
  • Once upon a time almost everything was called malignant fibrous histiocytoma; thus, it is listed as a common entity in some publications.

Most common:[3]

  • Liposarcoma.
  • Leiomyosarcoma.

Molecular testing

Main article: Molecular pathology
  • Molecular testing plays an important role in soft tissue pathology.
  • It is generally seen as an adjunct test that:[4]
    • Often is used to confirm the histomorphologic impression/quality control.
    • Frequently has some prognostic significance.
    • May directly affect treatment.

Translocations

Main article: Chromosomal translocations

Morphohistologic patterns

Main article: Morphologic patterns
Name Description DDx Image(s)
Storiform, AKA patternless pattern[5] whorled, cartwheel-like arrangement pleomorphic undifferentiated sarcoma, solitary fibrous tumour, dermatofibrosarcoma protuberans, dermatofibroma[6]
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
Herring bone. (WC)
Fascicular the long axis of the (spindle) cells are perpendicular to one another in adjacent bundles of cells leiomyoma, leiomyosarcoma
Fascicular pattern. (WC)
Biphasic nests of cells and stroma synovial sarcoma, DSRCT, alveolar RMS
DSRCT. (WC)

Notes:

  • Memory device: herring bone DDx MSF = MPNST, Synovial sarcoma, Fibrosarcoma.

Grading

  • Several systems exist.
  • The US-CAP advocates the use of the French system over the NCI system.
    • The French system is a better predictor metastases and mortality.[7]

French system

  • Formally known as the grading system from the French Federation of Cancer Centres Sarcoma Group (FNCLCC).

Overview

Components - overview:[7][8]

  1. Differentiation (score 1-3).
    • De facto, this is mostly the histologic type.
  2. Mitotic rate (score 1-3).
  3. Necrosis (score 0-2)

Obtaining a score:

  • Add all the points from the three components.

Scoring:

  • Grade 1 = 2-3.
  • Grade 2 = 4-5.
  • Grade 3 = 6-8.
Differentiation
  • Standardized for histologic types.
  • Most tumours = 3/3.

Exceptions:[8]

A group of tumours is not graded:[8]

Mitotic rate
  • 0-9 mitoses/10 HPF.
  • 10-19 mitoses/10 HPF.
  • >=20 mitoses/10 HPF.

Notes:

  • 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.
Necrosis
  • None = score 0.
  • <=50% of tumour = score 1.
  • >50% of tumour = score 2.

System used by some at MSH

Some pathologists at MSH use the system advocated by Costa et al..[9]

Scoring

  • Grade 1 = 1 point.
  • Grade 2 = 2 points.
  • Grade 3 = 3-4 points.

Components

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.

Stage

Main article: Cancer staging systems

Lymph node metastases in sarcomas

Main article: Lymph node metastasis

Sarcomas more likely to be found in the lymph nodes - mnemonic RACE For MS:[12]

DDx by history/site

Retroperiteum

  1. Liposarcoma.
  2. Undifferentiated pleomorphic sarcoma.
  3. Leiomyosarcoma.
  4. MPNST.

Note: Synovial sarcoma and fibrosarcoma are very rare in the retroperitoneum.

Young person - extremity sarcoma

  1. Epithelioid sarcoma.
  2. 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

Main article: Adipocytic tumours

This category includes:

  • Lipoma.
  • Liposarcoma.
  • Hibernoma.

Smooth muscle tumours

Main article: Smooth muscle tumours

IHC markers: desmin, SMA, H-caldemsin (most specific).

Leiomyosarcoma

Main article: Leiomyosarcoma

Microscopic

Features (summary):

  • Fasicular cellular spindle cell lesion with:
    • Nuclear atypia.
    • Necrosis.
    • High mitotic rate.

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.[13]

Pleomorphic undifferentiated sarcoma

  • Abbreviated PUS.
  • AKA Undifferentiated pleomorphic sarcoma, abbreviated UPS.
  • Previously known as malignant fibrous histiocytoma, abbreviated MFH.[14]
Main article: Pleomorphic undifferentiated sarcoma

Fibroblastic/myofibroblastic tumours

Main article: Fibroblastic/myofibroblastic tumours

This is a very large and important group of soft tissue lesions. It is covered in a separate article.

The grouping includes:

Perivascular tumours

This grouping includes only two:[15]

Vascular lesions

Main article: Vascular lesions

Vascular lesions are "too red"; they have too many RBCs.

They include:

Skeletal muscle tumours

Rhabdomyoma

Main article: Rhabdomyoma

Rhabdomyosarcoma

  • Abbreviated RMS.
Main article: Rhabdomyosarcoma

Comes it two main flavours:

  • Alveolar rhabdomyosarcoma.
  • Embryonal rhabdomyosarcoma.

The histology may be that of a small round cell tumour.

Chondro-osseous tumours

Main article: Chondro-osseous tumours

This grouping includes tumours derived from cartilage and bone.

Tumours of uncertain differentiation

Angiomatoid fibrous histiocytoma

Main article: Angiomatoid fibrous histiocytoma

Aggressive angiomyxoma

  • AKA deep aggressive angiomyxoma.
Main article: Aggressive angiomyxoma

Angiomyofibroblastoma

Main article: Angiomyofibroblastoma

Extrarenal malignant rhabdoid tumour

Main article: Extrarenal malignant rhabdoid tumour

Ewing sarcoma/PNET

Main article: Ewing sarcoma

Epithelioid sarcoma

Sarcomas with an epithelioid morphology are covered in epithelioid sarcomas.
Main article: Epithelioid sarcoma

Alveolar soft part sarcoma

Main article: Alveolar soft part sarcoma

Desmoplastic small round cell tumour

Main article: Desmoplastic small round cell tumour

Clear cell sarcoma

Main article: Clear cell sarcoma

Synovial sarcoma

Main article: Synovial sarcoma

Other

Granulocytic sarcoma

  • Common alternate terms: extramedullary leukemia,[17] myeloid sarcoma, chloroma.
  • Other terms:[18] myeloblastoma, chloromyeloma, chloromyelosarcoma, granulocytic leukosarcoma, or myelosarcoma.
Main article: Granulocytic sarcoma

See also

References

  1. ↑ Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 601-3. ISBN 978-0781765275.
  2. ↑ Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 598-604. ISBN 978-0781765275.
  3. ↑ Skubitz KM, D'Adamo DR (November 2007). "Sarcoma". Mayo Clin. Proc. 82 (11): 1409–32. PMID 17976362. http://www.mayoclinicproceedings.com/content/82/11/1409.long.
  4. ↑ Fletcher CD, Fletcher JA, Dal Cin P, Ladanyi M, Woodruff JM (July 2001). "Diagnostic gold standard for soft tissue tumours: morphology or molecular genetics?". Histopathology 39 (1): 100–3. PMID 11454050.
  5. ↑ Mangano WE, Cagle PT, Churg A, Vollmer RT, Roggli VL (August 1998). "The diagnosis of desmoplastic malignant mesothelioma and its distinction from fibrous pleurisy: a histologic and immunohistochemical analysis of 31 cases including p53 immunostaining". Am. J. Clin. Pathol. 110 (2): 191–9. PMID 9704618.
  6. ↑ Meister P, Höhne N, Konrad E, Eder M (July 1979). "Fibrous histiocytoma: an analysis of the storiform pattern". Virchows Arch A Pathol Anat Histol 383 (1): 31–41. PMID 224569.
  7. ↑ 7.0 7.1 Guillou L, Coindre JM, Bonichon F, et al. (January 1997). "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". J. Clin. Oncol. 15 (1): 350–62. PMID 8996162.
  8. ↑ 8.0 8.1 8.2 URL: http://www.cap.org/apps/docs/committees/cancer/cancer_protocols/2011/SoftTissue_11protocol.pdf. Accessed on: 12 April 2011.
  9. ↑ Costa J, Wesley RA, Glatstein E, Rosenberg SA (February 1984). "The grading of soft tissue sarcomas. Results of a clinicohistopathologic correlation in a series of 163 cases". Cancer 53 (3): 530–41. PMID 6692258.
  10. ↑ 10.0 10.1 Fong, Y.; Coit, DG.; Woodruff, JM.; Brennan, MF. (Jan 1993). "Lymph node metastasis from soft tissue sarcoma in adults. Analysis of data from a prospective database of 1772 sarcoma patients.". Ann Surg 217 (1): 72-7. PMC 1242736. PMID 8424704. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1242736/.
  11. ↑ URL: http://www.cap.org/apps/docs/committees/cancer/cancer_protocols/2011/SoftTissue_11protocol.pdf. Accessed on: 28 March 2012.
  12. ↑ URL: http://www.aippg.net/forum/f21/surgery-mnemonics-79897/. Accessed on: 23 March 2012.
  13. ↑ Luzar, B.; Calonje, E. (Jan 2010). "Cutaneous fibrohistiocytic tumours - an update.". Histopathology 56 (1): 148-65. doi:10.1111/j.1365-2559.2009.03447.x. PMID 20055912.
  14. ↑ URL: http://sarcomahelp.org/learning_center/mfh.html. Accessed on: 8 April 2011.
  15. ↑ Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 602. ISBN 978-0781765275.
  16. ↑ Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 627. ISBN 978-0781765275.
  17. ↑ Bakst, RL.; Tallman, MS.; Douer, D.; Yahalom, J. (Oct 2011). "How I treat extramedullary acute myeloid leukemia.". Blood 118 (14): 3785-93. doi:10.1182/blood-2011-04-347229. PMID 21795742.
  18. ↑ Eom, KS.; Kim, TY. (Mar 2011). "Intraparenchymal myeloid sarcoma and subsequent spinal myeloid sarcoma for acute myeloblastic leukemia.". J Korean Neurosurg Soc 49 (3): 171-4. doi:10.3340/jkns.2011.49.3.171. PMC 3085814. PMID 21556238. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3085814/.
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