Fig. 5

False-positive USG in a 62-year-old male with undifferentiated pleomorphic sarcoma. (a,b) Axial pre- and post-enhanced T1-weighted images revealed a large, heterogeneously enhancing mass (arrows) at the right gluteus medius and minimus with focal extension to the right iliac bone (dashed arrows). (c) On his postoperative USG, taken 9 months after wide resection, a 2.2-cm irregular ovoid-shaped lesion with internal heterogeneous echogenicity was observed in the subcutaneous layer of the right gluteus region. (d) No vascularity was detected based on color Doppler USG. As a result of these USG findings, the MRI examination was rescheduled. (e,f) Axial fat-saturated T2-weighted and enhanced T1-weighted images revealed increased signal intensity and enhancement at the right gluteus medius, gluteus minimus, and iliacus, indicative of radiation-induced myositis. However, no definite nodular-enhancing lesion corresponding to the USG findings was identified