Figure 1. A 41-year-old woman with cystic adenomyosis. (a) Axial T1 weighted MR image shows hyperintense cystic mass (arrows) abutting left side of the uterus (U). Solid structure (arrowheads) with small hyperintense foci was seen within the mass. (b) Axial and (c) sagittal T2 weighted images with fat saturation shows hyperintense solid structure (arrowheads) in the hypointense loculus. The interface between the mass and uterus was irregular and unclear. Note that signal voids bridge between the uterus and the mass (short arrows). Adenomyosis is recognized in the uterus (long arrows). (d) Axial contrast-enhanced T1 weighted image with fat saturation shows marked enhancement in the solid structure (arrowheads). (e) Photomicrograph of the cystic adenomyosis (haematoxylin and eosin, x10). The cystic adenomyosis (arrows) includes the protuberance with florid glandular differentiation (arrowheads). Adenomyosis noted in the uterine myometrium (long arrows). (f) Photomicrograph of the glandular protuberance within the cystic adenomyosis (haematoxylin and eosin, x40). Endometrioid glands vary in size lie in haemorrhagic cellular stroma with no malignant transformation. Therefore they were considered as simple endometrial hyperplasia.