Lipoma vs well-differentiated liposarcoma

There a number of features that can help distinguish between lipoma and well-differentiated liposarcoma. This article relates to superficial well-differentiated liposarcomas that typically occur in the extremities, also known as atypical lipomatous tumors, and not retroperitoneal liposarcoma.

Epidemiology

Demographic factors that favor well-differentiated liposarcoma are age >60 years and male sex .

Radiographic features

MRI

MRI can have 100% sensitivity for the diagnosis of well-differentiated liposarcomas, however, has a low positive predictive value due to overlap of imaging features with benign lipoma variants . Features that favor well-differentiated liposarcoma :

  • size >10 cm
  • percentage fat <75%
  • thick or nodular (>2 mm) septa
  • nodular/globular areas
  • prominent high T2 signal foci
  • prominent enhancement
  • associated non-adipose mass
  • lower limb location
  • intramuscular location

Features that favor lipoma :

  • size <10 cm
  • percentage fat >75%
  • no or few thin (<2 mm) septa
  • no or minimal enhancement
  • no or minimal high T2 signal foci
  • subcutaneous location