Retroperitoneal liposarcoma is a sub type of liposarcoma, a malignant tumour of mesenchymal origin that may arise in any fat-containing region of the body. It is one of the most common primary retroperitoneal neoplasms 2.
There are five histological types:
well-differentiated: ~54%, low grade
lipoma-like
inflammatory
sclerosing
myxoid: ~31%, 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 tumour.
Radiographic features
CT
heterogenous mass
varying amount of fat and soft tissue
multiple septae
enhancing soft tissue components
MRI
myxoid: hyperintense on T2WI with delayed post-contrast enhancement
Treatment
The primary treatment option is resection if possible. However, local recurrence is common and occurs in 2/3 of patients. This is usually a sign of incomplete resection and highlights the difficulty in discriminating liposarcomas from normal retroperitoneal fat.
Differential diagnosis
retroperitoneal leiomyosarcoma
retroperitoneal malignant fibrous histiocytoma
retroperitoneal fibrosarcoma
exophytic renal angiomyolipoma:
presence of a large vessel extending into the renal cortex suggestive of AML; liposarcomas are hypovascular
renal parenchymal defect at the site of tumour contact strongly favours the diagnosis of exophytic angiomyolipoma- claw sign
calcifications suggest liposarcoma 3