Fig. 3
Early detection of local recurrence using short-term USG in a 67-year-old male with undifferentiated pleomorphic sarcoma. (a) Initial USG revealed a well-defined hypoechoic mass in the left trapezius muscle. (b,c,d) Axial T2-, T1-, and enhanced T1-weighted MR images show a well-defined T2 high signal intensity mass with enhancement in the left trapezius muscle, indicating a residual tumor (arrows). Ill-defined infiltration and enhancement are observed at the medial aspect of the tumor, representing postexcisional changes with or without tumor infiltration (dashed arrow). This lesion was a residual mass observed after excision at our dermatology department and pathologically confirmed as sarcoma. The patient subsequently underwent wide excision performed by an orthopedic oncologist. (e) On his 9-month postoperative USG, a newly detected 1.1-cm well-defined hypoechoic nodule was observed at the medial margin of the flap. Consequently, his MRI examination was rescheduled. (f) An enhanced T1-weighted MR image revealed a prominent enhancing mass with signal characteristics similar to those of the initial lesion. (g,h) High b-value (b = 1000 s/mm2) and apparent diffusion coefficient map images revealed diffusion restriction in the corresponding lesion (arrows). Wide resection was performed, and the lesion was pathologically confirmed as a recurrent tumor