Myxoid Liposarcoma

History: 40 year old male with thigh “lump.”

Sagittal T1W MR of the thigh reveals a well circumscribed T1 isointense mass in the vastus medialis.

Sagittal T1W MR postcontrast with fat saturation reveals diffuse intense enhancement of the mass.

Axial T2W MR image with fat saturation reveals a predominantly myxoid appearing high signal mass with internal septations.

This is the typical appearance of a myxoid liposarcoma, which is  a malignancy of adipose tissue. Commonly they are composed of about 25% fat tissue, but they may not have fat tissue visible on imaging. Up to 75% of these occur in the deep tissues of the thigh. Myxoid liposarcoma is classically low signal on T1, high signal on T2, and homogeneously enhance avidly. They are common in the 4th-5th decades, but are the most common liposarcoma in patients less than 20 years old.

Credit to Quinn Meisinger, M.D. for this excellent case!