Imaging in retroperitoneal soft tissue sarcoma

Abstract

Patients with retroperitoneal sarcoma can present to a variety of clinicians with non-specific symptoms and retroperitoneal sarcomas can be incidental findings. Failure to recognize retroperitoneal sarcomas on imaging can lead to inappropriate management in non-specialist centers. Therefore it is critical that the possibility of retroperitoneal sarcoma should be considered with prompt referral to a soft tissue sarcoma unit. This review guides clinicians through a diagnostic pathway, introduces concepts in response assessment and new imaging developments.

Keywords: CT; MRI; diagnosis; retroperitoneum; soft tissue sarcoma.

Figure 1

Spectrum of retroperitoneal lipoma and liposarcoma appearances on contrast enhanced CT. Although rare, retroperitoneal lipoma can be seen as a relatively bland retroperitoneal mass (A, arrow). This appearance is not dissimilar to the bland fat density appearance of a well differentiated liposarcoma (B, arrow) and therefore biopsy is essential to confirm the diagnosis. Areas of differentiation appear as solid areas (C, *) which can sometimes be seen within areas of well differentiated tumor (C, arrow). Occasionally the whole mass can be dedifferentiated with no macroscopic fat evident (D, arrow)

Figure 2

Contrast enhanced CT appearances of retroperitoneal liposarcoma mimics. If a fat density retroperitoneal mass is associated with a renal cortical defect (A, arrow) and prominent vessels (A, dashed arrow) renal angiomyolipoma should be considered. Suprarenal fatty masses (B, arrow) with ground glass changes (B,*) may represent an adrenal myelolipoma

Figure 3

Contrast enhanced CT of a leiomyosarcoma of the inferior vena cava. Both an intraluminal (arrow) and exophytic component (*) are evident. Hepatic metastases (dashed arrow) are also seen

Figure 4

Contrast enhanced CT demonstrates typical appearances of retroperitoneal lymphoma. There is a bland retroperitoneal soft tissue mass which encases and displaces the renal vein (arrow) but does not efface it

Figure 5

Other retroperitoneal sarcoma subtypes. An avidly enhancing retroperitoneal mass (A, arrow) should raise suspicion for solitary fibrous tumor. The soft tissue mass (B) which invades psoas muscle (B, arrow) indicates the aggressive nature. This was biopsy proven malignant peripheral nerve sheath tumor

Figure 6

Coronal CT demonstrates a left sided well differentiated retroperitoneal liposarcoma (arrow) with extension into the inguinal canal (dashed arrow)