MR manifestations of uterine polypoid adenomyoma

Polypoid adenomyoma (PA) is an uncommon benign tumor of the uterus appearing as a submucosal polypoid mass, or rarely as a subserosal polypoid mass. PA should be differentiated from atypical polypoid adenomyoma or malignant uterine tumors. The purpose of our case series is to evaluate magnetic resonance (MR) manifestations of PA for the differential diagnosis. Seven cases with surgically proven PA, five submucosal, and two subserosal, were evaluated. MR imaging findings including contrast enhancement in six cases (four cases with dynamic contrast-enhanced MR study), diffusion-weighted imaging (DWI) in five cases, and susceptibility weighted imaging (SWI) in two cases were retrospectively reviewed. All seven lesions exhibited isointensity compared with the myometrium and 4 of 7 lesions (57%) contained high signal intensity hemorrhagic areas on T1-weighted images. On T2-weighted images, signal intensity was variable and all seven lesions contained cysts. None of five lesions with DWI exhibited high signal intensity compared with the normal myometrium. All six lesions showed intense contrast enhancement similar to that of the myometrium on post-contrast T1-weighted images. Punctate low intensity areas reflecting blood contents were revealed in all two lesions with SWI. Submucosal or subserosal polypoid masses containing hemorrhagic areas, and cysts reflecting functional endometrium and dilatation of endometrial glands are suggestive for PA. Intense contrast enhancement similar to that of the myometrium may be another characteristic finding for PA.