45-year-old presenting with gradual abdominal swelling.

Scanogram of the abdomen shows diffuse abdominal swelling with displacement of bowel loops displaced laterally. CT of the abdomen shows an ill-defined low density fat containing lesion occupying the entire abdomen and extending into the pelvis. Bowel loops are displaced and compressed anteriorly.

Second most common type of soft tissue sarcoma, representing 10-25% of all soft tissue sarcomas 

Patients usually present in their fifth decade with abdominal swelling and pain

Size is usually more than 5 cm at presentation

Histological types as per WHO (2002 guidelines

.:
o Well-differentiated and dedifferentiated liposarcoma (WDLPS / DDLPS)
o Myxoid and round cell liposarcoma (MLS and RCL)
o Pleomorphic liposarcoma (PLS)

Large lesions may appear as soft tissue masses.

Fat can be seen in lesions in extremity however it is difficult to appreciate in retroperitoneal lesions

Heterogeneous, multi-lobulated well-defined mass.

Identification of fat as echogenic foci can often be difficult and is nonspecific.

Large heterogeneous fat containing lesions with non-lipomatous components. Fat appears as low attenuation on CT (-100HU) and hyperintense on T1W images.

Multiple septae and enhancing soft tissue components are often identified.

Imaging appearance can often point to the subtype

• Well-differentiated and dedifferentiated liposarcoma:

Thick septa (>2mm) and enhancing nodular soft tissue nodules (<1cm) can be present. 

Have high water content can often be mistaken as cystic lesions.

Appear low signal intensity on T1 and high signal on T2.

Diffuse post contrast enhancement distinguishes these from truly cystic lesions.

Round cell subtype has a non-specific appearance on image.

Aggressive lesions with little or no fat.

Well circumscribed enhancing soft tissue lesions.


Surgical resection is the treatment of choice. 

References:
1. Matthyssens L, Creytens D, Ceelen W. Retroperitoneal Liposarcoma: Current Insights in Diagnosis and Treatment. Frontiers in Surgery. 2015;2.
2. O'Regan K, Jagannathan J, Krajewski K, Zukotynski K, Souza F, Wagner A et al. Imaging of Liposarcoma: Classification, Patterns of Tumor Recurrence, and Response to Treatment. American Journal of Roentgenology. 2011;197(1):W37-W43.
3. Murphey M, Arcara L, Fanburg-Smith J. Imaging of Musculoskeletal Liposarcoma with Radiologic-Pathologic Correlation. RadioGraphics. 2005;25(5):1371-1395.

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