55-year-old man with myxoid liposarcoma and post-surgical wound covered with lateral gastrocnemius flap after resection. Axial T2-weighted MR image with fat saturation shows homogenous hyperintensity (arrows) of irradiated region with well-defined margins best noted anteriorly. This differs from patchy enhancement (Fig. 9) attributed to infection. There is also some joint effusion in lateral recess of knee joint. Fem = left femur