Soft tissue lesions: Difference between revisions

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*Liposarcoma.
*Liposarcoma.
*Leiomyosarcoma.
*Leiomyosarcoma.
==Molecular testing==
*Molecular testing plays an important role in soft tissue pathology.
*It is generally seen as an adjunct test that is:<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 used to confirm the histomorphologic impression.
**Frequently has some prognostic significance.
**May directly affect treatment.


=Other=
=Other=

Revision as of 00:50, 31 May 2010

Soft tissue tumours strike fear in many pathologists as they are uncommon and may be difficult to diagnose.

WHO classification of soft tissue tumours

Morphologic grouping[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[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

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

Other

Neurofibromatosis

Comes in two flavours:

  1. NF1 (peripheral).
  2. NF2 (central).

NF1

Features (need 2/7 to diagnose):[5]

  • Two or more neurofibromas or one plexiform neurofibroma.
  • 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

Features (need 1/3 to diagnose):[6]

  1. Bilateral CNVIII masses on imaging.
  2. Unilateral CNVIII mass + first-degree relative with NF2.
  3. First-degree relative with NF2 and 2/4 of the following:
    1. Meningioma.
    2. Glioma.
    3. Schwannoma.
    4. Juvenile cataract.

Small round blue cell tumours (SRBCT)

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.

DDx

  • Neuroblastoma.
  • 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

Features:

  • Sheets of cells, very cellular.
  • Small cells ~ 2X RBC diameter.
  • Scant cytoplasm.
  • Coarse chromatin.
  • Nucleolus (???).
  • +/-Vascular.

Adipocytic tumours

Hibernoma

General

  • Consists of brown fat (present in the infants to generate heat).[7]
  • Benign.
  • Usually asymptomatic.[8]

Epidemiology

  • Young adults.

Gross

  • Well-circumscribed.
  • Lobulated and light-brown on sectioning.

Microscopic

Features:[9]

  • Large polygonal/oval cells:
    • Nucleus - central & small.[10]
      • Nucleoli typically prominent.[11]
    • Cytoplasm - multivacuolated, oval, eosinophilic, granular.

Image:

Liposarcoma

  • Most common malignant sarcoma in the retroperitoneum.

Microscopy

Features:

  • Lipoblasts:
    • Large sharply demarcated vacuole.
    • Nucleus:
      • Hyperchromatic (dark staining) nucleus.
      • Eccentric location.
      • Nuclear indentation.

Images:

IHC

  • IHC is of limited value.
  • S-100 +ve ~1/3 of the time.
  • Reticulin ???.

Smooth muscle tumours

Leiomyosarcoma

See gyne notes.

Microscopy

Features:

  • Nuclear atypia.
  • Necrosis.
  • Mitoses.

Fibroblastic/myofibroblastic tumours

Proliferative fasciitis

  • Need to write something here.

Hemangiopericytoma

General

  • Grouped with solitary fibrous tumour in the WHO classification; possibly the same tumour (?).[12]
  • 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.[13]
  • Oncogenic osteomalacia - assoc. with hemangiopericytoma.[14]

Presentation

  • Usually painless mass, slow enlargement.

Radiology

  • Intramedullary lytic mass.
  • May be well-circumscribed.
  • +/-Periosteal reaction.
  • +/-Sclerotic border.

May be worked-up with angiography to distinguish from a vascular malformation.[15]

Location

  • Usually extremities - femur or prox. tibial.[16]

Histology

Features:[17]

  • Hypervascular lesion - key diagnostic feature.[18]
    • 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

Features:[19][18]

  • Vimentin +ve (usually).
  • Desmin -ve (typical).
  • Factor VIII -ve (marks endothelium).
  • CD34 +ve.
    • CD34 usu. -ve in synovial sarcoma.
  • CD31 -ve (marks benign endothelium).
  • vWF (von Willebrand factor) -ve.

DDx

  • Other vascular tumours.
  • Vascular malformations.
  • Synovial sarcoma.

Desmoplastic fibroblastoma

  • AKA collagenous fibroma.[20]
  • Benign lesion.
  • Classically found in shoulder region.

IHC

  • Beta-catenin -ve.[21]
    • Significance ???

Vascular tumours

Kaposi sarcoma

General

  • Not really a sarcoma.
  • Caused by HHV-8.
  • Associated with immunodeficiency, e.g. HIV/AIDS.

Stages

It is seen in different stages:[22]

  1. Patch stage.
  2. Plaque stage.
  3. Nodular stage.
  4. Lymphangioma-like. (???)

Microscopic

Features:[23]

  • Vascular channels that anastomose.
  • +/-Nuclear atypia.
  • Hyaline globules - pale pink globs (that are paler than RBCs) - key feature.
  • +/-Hemosiderin deposits.

DDx:

  • Angiosarcoma (have many mitoses).

IHC

  • CD31 +ve, CD34 +ve, HHV-8 +ve.

Angiosarcoma

  • Malignant tumour.

Microscopic

Features:

  • Very many small capillaries or irregular shape lined with:
    • Atypical nuclei, pleomorphic nuclei.
  • Mitoses.
  • Cytoplasmic vacuoles.
    • Cells trying to form lumina - embryologic.

Hemangioendothelioma

  • Usually benign.

Microscopic

Features:[24]

  • Well-formed thin vascular channels on a fibrous stroma - key feature.
  • +/-Thrombosis.
  • +/-Calcification.
  • +/-Fibrosis.
  • +/-Myxoid change.

IHC

  • Factor VIII +ve.

Skeletal muscle tumours

Rhabdomyosarcoma

  • Often abbreviated RMS.
  • Most common paediatric sarcoma.
  • ~6% of all childhood cancer.

Histological subdivision:

  1. Alveolar rhabdomyosarcoma.
    • Usually young adults/adolescents.
    • Early mets common.
  2. Embryonal rhabdomyosarcoma.
    • Usual <10 years old.
    • Typically locally invasive.

Molecular and histologic subdivision:

  1. Translocation-positive alveolar RMS.
  2. Translocation-negative alveolar RMS.
  3. Embryonal RMS.

Notes:

  • Translocation-negative alveolar RMS shares characteristics with embryonal RMS.

Microscopy

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

Alveolar rhabdomyosarcoma

Common translocations (~80%):

  • t(1,13).
    • PAX3/FKHR fusion gene.
  • t(2,13).
    • PAX7/FKHR fusion gene.

Several uncommon translocations exist.

IHC

  • Desmin (best marker).
  • Actin.

Tumours of uncertain differentiation

Clear cell sarcoma

  • Known among pathologists as "soft-tissue melanoma" and "melanoma of the soft parts", as it has a strong morphological resemblance.[25]
    • 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.[26]

Microscopy

Features:[25]

  • Architecture: sheets or fascicular (bundles) arrangement.
  • Cells: Spindle cells or epithelioid cells.
  • Prominent nucleoli - basophilic.
  • Fibrous septae.
  • Uniform

Image:

IHC

Features:[25]

  • S100 +ve.
  • HMB-45 +ve.
  • Melan A (MART-1) +ve; sometimes -ve.
  • bcl-2 +ve.
  • CD57 +ve (usually).

Keratins:

  • EMA may be +ve.
  • CAM5.2 -ve.
  • AE1/AE3 -ve.

Molecular studies

  • Chromosomal translocation t(12;22)(q13;q12).[25]
    • Fusion transcripts:
      • EWSR1-ATF1.
      • EWSR1-CREB1 (GI tract associated).

Chondrosarcoma

  • May arise from an enchondroma.
  • Usually a good prognosis.

Microscopic

Features:

  • Resembles cartilage at low power.[27]
  • More cellular than cartilage... but relatively paucicellular compared to other sarcomas.

Images:

Grading

Features:[28]

  • Grade I: moderate cellularity +/- binucleated cells.
  • Grade III: nuclear pleomorphism, mitoses common.
  • Grade II: between Grade I and Grade III.

Synovial sarcoma

General

  • Does not arise from cartilage.[29]
  • Young adults or adolescents.

Microscopic

Comes in three flavours:[30][31]

  1. Spindle cell sarcoma with features of hemangiopericytoma, i.e. staghorn vessels.
  2. Biphasic synovial sarcoma:
    1. Spindle cells with features of hemangiopericytoma.
    2. Epitheliod glands or nests.
  3. Primative round cell type.

Images:

IHC

Features:[32]

  • Vimentin +ve + cytokeratin and/or EMA +ve.
  • CD99 +ve.

Others:

Molecular pathology

Unique translocation:

  • t(X;18)(p11.2;q11.2).[35]

See also

References

  1. ↑ WMSP PP.601-3.
  2. ↑ WMSP PP.598-604.
  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. ↑ URL: http://emedicine.medscape.com/article/1177266-overview. Accessed on: 3 May 2010.
  6. ↑ URL: http://emedicine.medscape.com/article/1178283-overview. Accessed on: 3 May 2010.
  7. ↑ WMSP P.605.
  8. ↑ Ahmed SA, Schuller I (December 2008). "Pediatric hibernoma: a case review". J. Pediatr. Hematol. Oncol. 30 (12): 900–1. doi:10.1097/MPH.0b013e318184e6dd. PMID 19131775.
  9. ↑ Chen DY, Wang CM, Chan HL (March 1998). "Hibernoma. Case report and literature review". Dermatol Surg 24 (3): 393–5. PMID 9537018.
  10. ↑ http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675(06)70271-6
  11. ↑ http://surgpathcriteria.stanford.edu/softfat/hibernoma/
  12. ↑ WMSP P.609.
  13. ↑ URL: http://emedicine.medscape.com/article/1255879-overview. Accessed on: 2 May 2010.
  14. ↑ URL: http://emedicine.medscape.com/article/1255879-overview. Accessed on: 2 May 2010.
  15. ↑ URL: http://emedicine.medscape.com/article/1255879-diagnosis. Accessed on: 2 May 2010.
  16. ↑ URL: http://emedicine.medscape.com/article/1255879-overview. Accessed on: 2 May 2010.
  17. ↑ URL: http://emedicine.medscape.com/article/1255879-diagnosis. Accessed on: 2 May 2010.
  18. ↑ 18.0 18.1 Enzinger & Weiss's Soft Tissue Tumors. 4th Ed. PP.1007-13. ISBN 0-323-01200-0.
  19. ↑ WMSP P.609.
  20. ↑ PMID 18271804.
  21. ↑ PMID 18544056.
  22. ↑ URL: http://www.histopathology-india.net/KS.htm. Accessed on: 31 January 2010.
  23. ↑ Klatt. AOP P.23.
  24. ↑ Klatt. AOP P.23.
  25. ↑ 25.0 25.1 25.2 25.3 Hisaoka M, Ishida T, Kuo TT, et al. (March 2008). "Clear cell sarcoma of soft tissue: a clinicopathologic, immunohistochemical, and molecular analysis of 33 cases". Am. J. Surg. Pathol. 32 (3): 452–60. doi:10.1097/PAS.0b013e31814b18fb. PMID 18300804.
  26. ↑ URL: http://www.informaworld.com/smpp/723576818-750600/ftinterface~db=all~content=a789166263~fulltext=713240928. Accessed on: 5 May 2010.
  27. ↑ Klatt. AOP P.417.
  28. ↑ WMSP P.643.
  29. ↑ WMSP P.627.
  30. ↑ WMSP P.627.
  31. ↑ Schaal CH, Navarro FC, Moraes Neto FA (2004). "Primary renal sarcoma with morphologic and immunohistochemical aspects compatible with synovial sarcoma". Int Braz J Urol 30 (3): 210–3. PMID 15689250. http://www.brazjurol.com.br/may_june_2004/Schaal_ing_210_213.htm.
  32. ↑ WMSP P.627.
  33. ↑ 33.0 33.1 Horvai AE, Kramer MJ, O'Donnell R (June 2006). "Beta-catenin nuclear expression correlates with cyclin D1 expression in primary and metastatic synovial sarcoma: a tissue microarray study". Arch. Pathol. Lab. Med. 130 (6): 792–8. PMID 16740029.
  34. ↑ Ng TL, Gown AM, Barry TS, et al. (January 2005). "Nuclear beta-catenin in mesenchymal tumors". Mod. Pathol. 18 (1): 68–74. doi:10.1038/modpathol.3800272. PMID 15375433.
  35. ↑ URL: http://www.ncbi.nlm.nih.gov/omim/300813. Accessed on: 30 May 2010.
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