Figure 13. Leiomyosarcoma at 26 weeks gestation. US showed a left-sided pelvic mass, but the origin and extent of the mass could not be determined. Coronal fat-suppressed T2-weighted image shows a bilobed high-signal-intensity mass (arrows), which appears to be contiguous to the uterus. On the basis of the MR imaging findings, the diagnosis of leiomyoma was suggested; however, a myxoid leiomyosarcoma was found at surgery 2 days later.