Coexistence of endometrioid adenocarcinoma in atypical polypoid adenomyoma

Atypical polypoid adenomyoma (APA) is a rare polypoid tumor of the uterus composed of atypical endometrial glands and smooth muscle cells. Concomitant development of endometrial adenocarcinoma in APA remains infrequent. We report a case of the coexistence of endometrioid adenocarcinoma in APA. A 41-year-old patient presented with abnormal genital bleeding. A polypoid mass was extruded from the external cervical os. She underwent transcervical resection of the polypoid mass arising from the lower uterine segment. Pathological examination revealed APA with the foci of well-differentiated endometrioid adenocarcinoma. Subsequently, she underwent total hysterectomy and bilateral salpingo-oophorectomy. No residual malignant lesions were found. Awareness of the close association of APA with the development of endometrial cancer is warranted. A meticulous pathological evaluation of specimen of APA is necessary for the detection of the coexistence of endometrial cancer.