Liposarcoma

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Liposarcoma is a malignant adipocytic tumour.

Liposarcoma
Diagnosis in short

Liposarcoma. H&E stain.
LM lipoblasts - key feature, chicken wire-like vascular, +/-myxoid background, cell size variation, thick fibrous septa (important low power feature)
Subtypes dedifferentiated liposarcoma, myxoid liposarcoma (includes round cell liposarcoma), mixed-type liposarcoma, pleomorphic liposarcoma, liposarcoma not otherwise specified (NOS), spindle cell liposarcoma
LM DDx pleomorphic undifferentiated sarcoma
IHC S-100 +ve
Molecular t(12;16)(q13;p11) / TLS-CHOP -- for myxoid liposarcoma
Site soft tissue esp. retroperiteoneum
Prevalence most common retroperitoneal sarcoma, uncommon overall
Radiology thick septae or nodules in a fatty appearing lesion
Prognosis poor

General

  • Most common malignant sarcoma in the retroperitoneum.
  • Not all (large) retroperitoneal adipocytic tumours are liposarcomas.

Notes:

Gross

  • Thick fibrous septa

Radiology:[1]

  • Fibrous septa or nodules.[2]
  • Myoid liposarcoma - high signal (due to high water content).[2]

Microscopic

Features:

  • Lipoblasts - key feature.
    • Large sharply demarcated vacuole.
    • Nucleus:
      • Hyperchromatic (dark staining) nucleus.
      • Eccentric location.
      • Nuclear indentation.
  • Chicken wire-like vascular.
  • +/-Myxoid background.
  • Cell size variation.
  • Thick fibrous septa - important low power feature.[1]

DDx:

Images

  • Dediff. liposar. - shows dediff. component - intermed. mag. (WC)

  • Dediff. liposarc. - high mag. (WC)

  • Dediff. liposarc. - very high mag. (WC)

  • Dediff. liposarc. - lipoblasts - very high mag. (WC)

  • Myxoid liposarcoma. (WC)

  • Myxoid liposarcoma. (WC)

www:

Subtypes

Main subtypes:[3]

  • Dedifferentiated liposarcoma.
  • Myxoid liposarcoma.
    • Round cell liposarcoma - a subtype of myxoid liposarcoma[4] that has a worse prognosis;[5] characterized by regions of high cellularity.
  • Mixed-type liposarcoma.
  • Pleomorphic liposarcoma.
  • Liposarcoma not otherwise specified (NOS).

Additional reported type:

  • Spindle cell liposarcoma.[6]

Myxoid liposarcoma

  • AKA myxoid/round cell liposarcoma.
  • AKA round cell liposarcoma.
Gross

Location:[7]

  • 90% in lower limb.
  • 81% deep.
Microscopic

Features:

  • Chickenwire-type blood vessels.
  • Clear spaces.
  • Adipocytes - may be rare.

DDx:

Images:

Molecular

Typically has a translocation:

  • t(12;16)(q13;p11) TLS-CHOP.[9]
  • May have the translocation usually seen in clear cell sarcoma:
  • t(12;22)(q13;q12) EWS-ATF1.[10]

Dedifferentiated liposarcoma

  • Has an undifferentiated component that, if seen alone, would be diagnosed as pleomorphic undifferentiated sarcoma.
  • The diagnosis depends on the presence of the differentiated component of the tumour, i.e. the presence of lipoblasts.

IHC

  • MDM2 +ve.[11]
  • CDK4 +ve.
  • S-100 +ve ~1/3 of the time.[11]

See also

References

  1. ↑ 1.0 1.1 Hosono, M.; Kobayashi, H.; Fujimoto, R.; Kotoura, Y.; Tsuboyama, T.; Matsusue, Y.; Nakamura, T.; Itoh, T. et al. (Mar 1997). "Septum-like structures in lipoma and liposarcoma: MR imaging and pathologic correlation.". Skeletal Radiol 26 (3): 150-4. PMID 9108224.
  2. ↑ 2.0 2.1 2.2 Murphey, MD.; Arcara, LK.; Fanburg-Smith, J.. "From the archives of the AFIP: imaging of musculoskeletal liposarcoma with radiologic-pathologic correlation.". Radiographics 25 (5): 1371-95. doi:10.1148/rg.255055106. PMID 16160117.
  3. ↑ Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 601. ISBN 978-0781765275.
  4. ↑ Smith, TA.; Easley, KA.; Goldblum, JR. (Feb 1996). "Myxoid/round cell liposarcoma of the extremities. A clinicopathologic study of 29 cases with particular attention to extent of round cell liposarcoma.". Am J Surg Pathol 20 (2): 171-80. PMID 8554106.
  5. ↑ Conyers, R.; Young, S.; Thomas, DM. (2011). "Liposarcoma: molecular genetics and therapeutics.". Sarcoma 2011: 483154. doi:10.1155/2011/483154. PMID 21253554.
  6. ↑ Dei Tos, AP.; Mentzel, T.; Newman, PL.; Fletcher, CD. (Sep 1994). "Spindle cell liposarcoma, a hitherto unrecognized variant of liposarcoma. Analysis of six cases.". Am J Surg Pathol 18 (9): 913-21. PMID 8067512.
  7. ↑ Moreau, LC.; Turcotte, R.; Ferguson, P.; Wunder, J.; Clarkson, P.; Masri, B.; Isler, M.; Dion, N. et al. (Apr 2012). "Myxoid\Round Cell Liposarcoma (MRCLS) Revisited: An Analysis of 418 Primarily Managed Cases.". Ann Surg Oncol 19 (4): 1081-1088. doi:10.1245/s10434-011-2127-z. PMID 22052112.
  8. ↑ Sung, MS.; Kang, HS.; Suh, JS.; Lee, JH.; Park, JM.; Kim, JY.; Lee, HG.. "Myxoid liposarcoma: appearance at MR imaging with histologic correlation.". Radiographics 20 (4): 1007-19. doi:10.1148/radiographics.20.4.g00jl021007. PMID 10903690.
  9. ↑ Knight, JC.; Renwick, PJ.; Dal Cin, P.; Van den Berghe, H.; Fletcher, CD. (Jan 1995). "Translocation t(12;16)(q13;p11) in myxoid liposarcoma and round cell liposarcoma: molecular and cytogenetic analysis.". Cancer Res 55 (1): 24-7. PMID 7805034.
  10. ↑ Suzuki, K.; Matsui, Y.; Endo, K.; Kubo, T.; Hasegawa, T.; Kimura, T.; Ohtani, O.; Yasui, N. (Nov 2010). "Myxoid liposarcoma with EWS-CHOP type 1 fusion gene.". Anticancer Res 30 (11): 4679-83. PMID 21115923.
  11. ↑ 11.0 11.1 Mariño-Enríquez, A.; Hornick, JL.; Dal Cin, P.; Cibas, ES.; Qian, X. (Feb 2014). "Dedifferentiated liposarcoma and pleomorphic liposarcoma: a comparative study of cytomorphology and MDM2/CDK4 expression on fine-needle aspiration.". Cancer Cytopathol 122 (2): 128-37. doi:10.1002/cncy.21362. PMID 24227706.
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