Atypical Polypoid Adenomyofibroma of the Endometrium Presenting With Severe Abnormal Uterine Bleeding: A Case Report.

Atypical polypoid adenomyoma (APA) of the endometrium is an exceedingly rare biphasic uterine lesion characterized by atypical endometrial glands embedded within fibromuscular stroma. The overlapping histologic features of premalignant and malignant endometrial lesions require accurate diagnosis to avoid overtreatment. APA is a polypoid lesion that consists of atypically complex endometrial glands that may or may not have squamous morules in a benign myomatous or fibromyomatous stroma. We present a case of a 42-year-old multiparous female with severe abnormal uterine bleeding resulting in symptomatic anemia requiring transfusion. Imaging suggested adenomyosis, and hysterectomy was performed in 2025 for definitive management. Histological examination revealed an APA arising in a secretory endometrium with coexisting adenomyosis and leiomyomata. In addition, a high-grade squamous intraepithelial lesion involving the cervix was identified. Postoperatively, the patient was placed on long-term surveillance with annual vaginal cytology for 25 years due to the presence of cervical HSIL. This case highlights the rarity of APA and underscores the importance of histologic evaluation when persistent abnormal uterine bleeding remains unexplained by imaging or biopsy.