MRI features of a soft tissue lipoma of intermuscular location between the rhomboid major muscle anteriorly and trapezius muscle posteriorly.

On imaging, the primary differential diagnoses are:

• liposarcoma: 
  • thick septa with enhancement
  • or evidence of local invasion
• normal adipose tissue:
  • usually non-encapsulated fatty mass
  • indistinguishable from the adjacent fatty tissue

The differentiation between intermuscular and intramuscular lipomas can be difficult too.