Soft tissue
Adipose tissue
Dedifferentiated liposarcoma

Author: Vijay Shankar, M.D. (see Authors page)

Revised: 10 August 2016, last major update August 2012

Copyright: (c) 2002-2016,, Inc.

PubMed Search: Dedifferentiated liposarcoma [title]

Cite this page: Dedifferentiated liposarcoma. website. Accessed October 21st, 2016.
Definition / General
  • Well differentiated liposarcoma with abrupt transition to dedifferentiated (high grade or low grade) morphology
  • Older adults
  • Occurs in up to 10% of well differentiated liposarcomas, more often retroperitoneal than superficial tumors
  • Dedifferentiated component usually is in recurrent or metastatic foci; possibly in original excision
  • More common in retroperitoneal lesions or spermatic cord, also in extremity tumors
  • Rare in subcutaneous tumors
Case Reports
  • Better prognosis than other high grade pleomorphic sarcomas (Am J Surg Pathol 1994;18:1213), but still recurs in 40 - 75%, metastasizes in 10 - 15%, causes death in 30 - 50% (Am J Surg Pathol 1997;21:271)
  • Metastases associated with low or high grade dedifferentiation (have similar behavior), those with myxofibrosarcoma-like features are rapidly fatal (Mod Pathol 2005;18:976)
  • Must rule out dedifferentiated liposarcoma in any retroperitoneal sarcoma by (1) adequate sampling, particularly of peripheral areas, (2) cytogenetics, (3) immunostaining for MDM2 and CDK4 or molecular testing for 12q13-15 amplification
  • Retroperitoneal dedifferentiated liposarcomas have higher rates of local recurrence and disease specific death rates (Curr Opin Oncol 2011;23:373)
Clinical Images

Images hosted on other servers:

Intraoperative image of axillary tumor

Gross Description
  • Large firm mass (may resemble “fish-flesh”) with coarse lobulation, often surrounded by benign appearing well differentiated component
Gross Images

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Various images

Micro Description
  • Well differentiated and dedifferentiated components, often with abrupt transition
  • Dedifferentiated component is cellular, nonlipogenic sarcoma with 5+ mitotic figures / 10 HPF
  • Usually high grade, often resembles MFH with short fascicles of spindled and pleomorphic cells
  • Heterologous elements in 10%
  • Less common is low grade tumor resembling fibromatosis or well differentiated fibrosarcoma
  • Metastases: usually contain dedifferentiated component only
  • Variant: neural-like whorling growth pattern and metaplastic bone formation (Cancer Genet Cytogenet 2007;172:147, Histopathology 1998;33:414, Am J Surg Pathol 1998;22:945)
Micro Images

Images hosted on PathOut servers:

Dedifferentiated liposarcoma

Fibromatosis-like areas

Hemangiopericytoma-type pattern

MFH-like areas

Neural appearance

sarcomatous elements

Storiform pattern

Images hosted on other servers:

Various images

Osteosarcomatous differentiation

Fibrosarcoma and solitary fibrous tumor-like patterns

Leiomyosarcomatous differentiation in retroperitoneal tumor with hCG production

H&E and MDM2 staining

MFH-like areas

Paraganglioma-like pattern

Cytology Description
  • Hypercellular with multinucleated, pleomorphic giant cells with abundant cytoplasm, small clusters of cells with high N / C ratio, spindled cells with elongated nuclei (Acta Cytol 2001;45:641)
  • Occasional osteoclast type giant cells (Cytojournal 2010;7:5)
Cytology Images

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FNAB of dedifferentiated liposarcoma

Positive Stains
Molecular / Cytogenetics Description
  • MDM2+, CDK4+
  • 12q14 amplification, often due to supernumerary ring or giant chromosome derived from 12q13-15 region - also found in tumors with whorling growth pattern (Cancer Genet Cytogenet 2007;172:147)
Molecular / Cytogenetics Images

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FISH studies performed on the
FNA biopsy cell-block sections
of dedifferentiated liposarcoma

Differential Diagnosis
  • Atypical angiomyolipoma: atypical smooth muscle may resemble sarcoma, but involves kidney, has abnormal blood vessels, HMB45+
  • Fibrosarcoma: no well differentiated component, no 12q13-15 amplification
  • Leiomyosarcoma: no well differentiated component, no 12q13-15 amplification
  • MFH-pleomorphic: retroperitoneal tumors may really be dedifferentiated liposarcomas (Mod Pathol 2003;16:256)
  • MPNST: no well differentiated component, no 12q13-15 amplification
  • Pleomorphic liposarcoma: has lipoblasts
  • Rhabdomyosarcoma: no well differentiated component, no 12q13-15 amplification
Additional References