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.
Answer: C. Retroperitoneal liposarcoma.
- 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.
CT and MR
- 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:
- Predominantly fat containing lesions.
- Thick septa (>2mm) and enhancing nodular soft tissue nodules (<1cm) can be present.
• Myxoid and round cell liposarcoma:
- 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.
• Pleomorphic liposarcoma:
- Aggressive lesions with little or no fat.
- Well circumscribed enhancing soft tissue lesions.
Surgical resection is the treatment of choice.
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.