Liposarcoma

Liposarcomas are malignant tumours of fatty tissue and are the malignant counterpart to a benign lipoma. They are the second commonest type of soft-tissue sarcoma.

Liposarcomas are typically found in adults and are rare in children, typically between the ages of 40 and 60.

It varies accordingly to the tumour location, usually related to a lump mass when involving the subcutaneous and extremities, and a vague discomfort when intraabdominal or intrathoracic. 

Thought to originate from mesenchymal cells, they are classified histologically into five types 1:

Location

They are usually seen in the extremities (75%), most commonly the thigh, and are less commonly seen in the retroperitoneum, groin or elsewhere 2,9 (see: retroperitoneal liposarcoma).

CT

Liposarcomas have three CT patterns based on amount and distribution of fat in tumour:

  • solid: attenuation over +20 HU
  • mixed: areas of less than -20 HU and areas of over +20 HU
  • pseudocystic: homogenous density between –20 and +20 HU

CT findings favouring a liposarcoma over a lipoma include:

  • inhomogeneous attenuation, with evidence of significant amounts of soft-tissue within the fatty mass
  • poor definition of adjacent structures
  • evidence of infiltration or invasion of mediastinal structures
  • calcification 8
MRI

MRI appearance, as with CT, varies depending on the grade and amount of fatty tissue.

Low grade lesions (atypical lipomas) are almost entirely fat signal with however thick septa, enhancement or evidence of local invasion. These features are used to distinguish these from simple lipomas 2.

The higher grade lesions are often devoid of macroscopic fat and have appearances similar to other sarcomas.

Both treatment and prognosis vary with location and grade.

Extremity liposarcomas, especially when well differentiated (atypical lipoma or atypical intramuscular lipoma) are indolent but nonetheless have a tendency to locally recur (0-69% of the time 2. The rate of recurrence is higher for deep lesions compared to superficial ones.

High grade lesions, especially those of the retroperitoneum have poor prognosis, with recurrence rates between 63-91% 2.

Surgical treatment is with wide local excision, which accounts at least in part for the more favorable outcome of extremity lesions.

General imaging differential considerations include:

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Article information

rID: 1589
Section: Pathology
Synonyms or Alternate Spellings:
  • Liposarcoma: general

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Cases and figures

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    Case 1: retroperitoneal
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    Case 2
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    Case 4: in a paediatric patient
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    Case 5
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    Case 6: intraperitoneal
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    Case 7: scapular region - ultrasound
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    Case 8
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    Case 9: myxoid liposarcoma
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    Case 10: mediastinal
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