A 46-year-old woman presents with a history of retroperitoneal liposarcoma status postresection.

Fig. 107.1 (A) Axial and (B) coronal contrast-enhanced CT images show a rounded, relatively homogeneous mass that measures water density by Hounsfield units in the retroperitoneal region adjacent to the left psoas muscle (arrow).

Metastatic liposarcoma with pseudocystic sign

• Seroma
  
• Retroperitoneal lymphocele
  
• Abdominal abscess
  
• Necrotic solid tumor
  
• Lymphangioma

Liposarcoma is a malignancy of adipose cells. It is the most common primary retroperitoneal tumor and the second most common soft tissue sarcoma in adults. Liposarcomas make up 95% of all fatty retroperitoneal tumors. They are usually seen in patients ages 40 to 60 years and occur more commonly in men than in women.