retroperitoneal liposarcoma

Retroperitoneal liposarcoma is a subtype of liposarcoma and is a malignant tumor of mesenchymal origin that may arise in any fat-containing region of the body. It is one of the most common primary retroperitoneal neoplasms.

Epidemiology

Most cases occur in patients at the 5-7 decades of life, with no gender predilection .

Liposarcomas represent the most common variety of malignant retroperitoneal tumor.

Pathology

Histology

There are five histological types:

  • well-differentiated: ~55%, low grade
    • lipoma-like
    • inflammatory
    • sclerosing
  • myxoid: ~30%, low-to-intermediate grade
  • pleomorphic: high grade
  • round cell: high grade
  • dedifferentiated: high grade

Metastatic disease is haematogenous and the extent of metastases is related to the histological grade of the tumor.

Radiographic features

CT
  • varying amount of fat and soft tissue
    • from purely fat with rare thin septa (usually low-grade lesions) to a very heterogeneous mass with extensive amounts of soft tissue component (usually high-grade lesions)
  • multiple septa
  • enhancing soft tissue components
MRI
  • myxoid type:
    • T2: hyperintense - myxoid gelatinous components
    • C+ (Gd): delayed post-contrast enhancement

Treatment and prognosis

The primary treatment option is resection if possible. However, local recurrence is common and occurs in two-thirds of patients. This is usually a sign of incomplete resection and highlights the difficulty in discriminating liposarcomas from normal retroperitoneal fat.

Differential diagnosis