Fig. 1

a Sagittal T2-weighted MRI shows a multilocular cystic mass, which is clearly delineated in the pelvis (maximum diameter approximately 20 cm). The uterus measures 80 mm in height, 55 mm in body length, and 6 mm in cavity thickness. b An ultrasound demonstrates the pelvic mass (diameter approximately 13 cm) containing a multilocular cyst without mural nodules. c Gross appearance, the tumor measures 19.0 cm x 14.0 cm x 8.5 cm. The inner surface of the cyst is mostly smooth, with areas of irregular thickening of the cyst wall, including yellowish mucoid substance