Soft tissue lesions

From Libre Pathology
Revision as of 13:25, 17 May 2010 by Michael (talk | contribs) (create)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to navigation Jump to search

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.

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 ???.

Leiomyosarcoma

See gyne notes.

Microscopy

Features:

  • Nuclear atypia.
  • Necrosis.
  • Mitoses.

Hemangiopericytoma

General

  • Grouped with solitary fibrous tumour in the WHO classification; possibly the same tumour (?).[3]
  • 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.[4]
  • Oncogenic osteomalacia - assoc. with hemangiopericytoma.[5]

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.[6]

Location

  • Usually extremities - femur or prox. tibial.[7]

Histology

Features:[8]

  • Hypervascular lesion - key diagnostic feature.[9]
    • 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:[10][9]

  • 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.[11]
  • Benign lesion.
  • Classically found in shoulder region.

IHC

  • beta-catenin -ve.[12]
    • Significance ???


Neurofibromatosis

Comes in two flavours:

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

NF1

Features (need 2/7 to diagnose):[13]

  • 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):[14]

  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.

Proliferative fasciitis

  • Need to write something here.

Hibernoma

General

  • Consists of brown fat (present in the infants to generate heat).[15]
  • Benign.
  • Usually asymptomatic.[16]

Epidemiology

  • Young adults.

Gross

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

Microscopic

Features:[17]

  • Large polygonal/oval cells:
    • Nucleus - central & small.[18]
      • Nucleoli typically prominent.[19]
    • Cytoplasm - multivacuolated, oval, eosinophilic, granular.

Image:

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.

Microscopic

Features:

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

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:[20]

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

Microscopic

Features:

  • Vascular channels that anastomose (low grade).
  • +/-Nuclear atypia (high grade).

DDx:

  • Angiosarcoma (have many mitoses).

IHC

  • CD31+, CD34+, HHV-8+.

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.

Clear cell sarcoma

  • Known among pathologists as "soft-tissue melanoma" and "melanoma of the soft parts", as it has a strong morphological resemblance.[21]
    • 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.[22]

Microscopy

Features:[21]

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

Image:

IHC

Features:[21]

  • 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).[21]
    • Fusion transcripts:
      • EWSR1-ATF1.
      • EWSR1-CREB1 (GI tract associated).

See also

References

  1. ↑ WMSP PP.601-3.
  2. ↑ WMSP PP.598-604.
  3. ↑ WMSP P.609.
  4. ↑ URL: http://emedicine.medscape.com/article/1255879-overview. Accessed on: 2 May 2010.
  5. ↑ URL: http://emedicine.medscape.com/article/1255879-overview. Accessed on: 2 May 2010.
  6. ↑ URL: http://emedicine.medscape.com/article/1255879-diagnosis. Accessed on: 2 May 2010.
  7. ↑ URL: http://emedicine.medscape.com/article/1255879-overview. Accessed on: 2 May 2010.
  8. ↑ URL: http://emedicine.medscape.com/article/1255879-diagnosis. Accessed on: 2 May 2010.
  9. ↑ 9.0 9.1 Enzinger & Weiss's Soft Tissue Tumors. 4th Ed. PP.1007-13. ISBN 0-323-01200-0.
  10. ↑ WMSP P.609.
  11. ↑ PMID 18271804.
  12. ↑ PMID 18544056.
  13. ↑ URL: http://emedicine.medscape.com/article/1177266-overview. Accessed on: 3 May 2010.
  14. ↑ URL: http://emedicine.medscape.com/article/1178283-overview. Accessed on: 3 May 2010.
  15. ↑ WMSP P.605.
  16. ↑ 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.
  17. ↑ Chen DY, Wang CM, Chan HL (March 1998). "Hibernoma. Case report and literature review". Dermatol Surg 24 (3): 393–5. PMID 9537018.
  18. ↑ http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675(06)70271-6
  19. ↑ http://surgpathcriteria.stanford.edu/softfat/hibernoma/
  20. ↑ URL: http://www.histopathology-india.net/KS.htm. Accessed on: 31 January 2010.
  21. ↑ 21.0 21.1 21.2 21.3 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.
  22. ↑ URL: http://www.informaworld.com/smpp/723576818-750600/ftinterface~db=all~content=a789166263~fulltext=713240928. Accessed on: 5 May 2010.
Retrieved from "https://librepathology.org/w/index.php?title=Soft_tissue_lesions&oldid=196"