A liposarcoma is a maligant tumour of fatty tissue. It is the malignant counterpart to the lipoma. They are the second most commonest type of soft tissue sarcoma 4.
Demographics and clinical presentation
Liposarcomas are typically found in adults, typically between the ages of 40 and 60, and are usually seen in the extremities or retroperitoneum 2 (see retroperitoneal tumours, and retroperitoneal liposarcoma)
Thought to originate from mesenchymal cells. They are histologically are classified into 5 types 1:
- well-differentiated (well differentiated liposarcoma) : commonest : ~ 50% 4; has the highest amount of fat content and is also known as an atypical lipoma , low grade
- myxoid (myxoid liposarcoma) : 2nd commonest ; intermediate grade
- round cell / de-differentiated (de-differentied liposarcoma) : high grade, aggressive with frequent metastases
- pleomorphic (pleomorhpic liposarcoma) : least common ; high grade, aggressive with frequent metastases
- mixed (mixed liposarcoma) :
Liposarcomas have three CT patterns based on amount and distribution of fat in tumour :
- solid : attenuation > + 20 HU
- mixed : areas of < -20 HU and areas of > + 20 HU
- pseudocystic : homogenous density between – 20 and + 20 HU
CT findings favouring a liposarcoma from 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
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 septae, 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.
Treatment and prognosis
Both treatment and prognosis varies 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 - higher rates in deep lesions c.f to superficial lesions)
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 differential considerations include
- 1. Kumar V, Abbas AK, Fausto N. Robbins and Cotran pathologic basis of disease. W B Saunders Co. (2005) ISBN:0721601871. Read it at Google Books - Find it at Amazon
- 2. Gaskin CM, Helms CA. Lipomas, lipoma variants, and well-differentiated liposarcomas (atypical lipomas): results of MRI evaluations of 126 consecutive fatty masses. AJR Am J Roentgenol. 2004;182 (3): 733-9. AJR Am J Roentgenol (citation) - Pubmed citation
- 3. Jelinek JS, Kransdorf MJ, Shmookler BM et-al. Liposarcoma of the extremities: MR and CT findings in the histologic subtypes. Radiology. 1993;186 (2): 455-9. Radiology (citation) - Pubmed citation
- 4. 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 - Pubmed citation
- 5. Kransdorf MJ, Bancroft LW, Peterson JJ et-al. Imaging of fatty tumors: distinction of lipoma and well-differentiated liposarcoma. Radiology. 2002;224 (1): 99-104. doi:10.1148/radiol.2241011113 - Pubmed citation
- 6. Eurorad teaching files : Pleomorphic liposarcoma of the pectoralis major muscle Case 8794
Synonyms & Alternative Spellings
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|Liposarcoma : general||✗|