Abstract
Uterine adenosarcoma is a rare, low-grade malignant tumor that usually arises from the endometrium and presents as a large polypoid mass occupying the endometrial cavity. A correct histopathological diagnosis of adenosarcoma from a small specimen is often difficult, and pre-operative MR imaging findings are generally not specific enough to establish an adenosarcoma diagnosis. A 60-year-old nulliparous woman was referred to our hospital who presented with vaginal bleeding. Her medical history was notable for type 2 diabetes mellitus and hypertension. Upon pelvic examination, a large endometrial polyp prolapsing through the cervix and vagina was observed while she was bleeding profusely. We performed a biopsy on the polyp, but the pathological diagnosis showed no malignancy. On MR imaging, the tumor presented both low and high signal intensities on T2WI, low signal intensity on T1WI, and a slightly high DWI signal intensity. Therefore, a prolapsed leiomyoma was suspected, and a hysteroscopic tumor excision was performed. The pathological examination found that the tumor was a uterine adenosarcoma. We thereafter performed an abdominal total hysterectomy with a bilateral salpingo-oophorectomy. The final diagnosis was a uterine adenosarcoma, T1aN0M0. In postmenopausal women with diabetes, where the pathological biopsy findings and imaging of a polypoidal mass with abnormal vaginal bleeding do not lead to a suspected malignant neoplasm, it is still important to remove the tumor and examine it in order to attain a current diagnosis because it may be a rare, low-grade malignant neoplasm, such as an adenosarcoma.