Abstract
The uterus is formed by paramesonephric duct fusion during embryonic development. Rare mesonephric remnants lead to hyperplasia and mesonephric adenocarcinoma. We report a case of adenocarcinoma with mesonephric hyperplasia that was difficult to diagnose. We report a case of a 53-year-old, para 2, woman who was referred to our hospital because of irregular vaginal bleeding. She was diagnosed with endometrial cancer by biopsy because of endometrial thickening. Furthermore, a 5-cm localized adenomyosis lesion was observed in the uterine cervix on contrast MRI, and stage IA endometrial cancer was suspected. We performed cervical conization. Histopathology revealed uterine cervical cancer, possibly diffuse mesonephric hyperplasia adenocarcinoma, and cervical-endometrial curettage revealed endometrioid adenocarcinoma Grade 1. Suspecting cervical mesonephric adenocarcinoma, we performed radical hysterectomy with bilateral salpingo-oophorectomy. We visually confirmed several yellow pea-sized polyps protruding from the uterine isthmus; however, the myometrium and uterine cervix were normal. HE staining confirmed the 5-cm cervical lesion. Aggregates of cysts containing hyaline were present, but were not atypical. The adenocarcinoma was localized in the polyps protruding from the lumen, and the final diagnosis was endometrial cancer (endometrioid adenocarcinoma, Grade 1, pT1aN0M0 + diffuse mesonephric hyperplasia). According to the Treatment Guidelines for Endometrial Cancer, it is in the low-risk group, and additional treatments are not recommended. In cases of cervical mesonephric adenocarcinoma, additional treatment is required according to the Treatment Guidelines for Cervical Cancer. Therefore, we evaluated this case at the Meeting of the Japan Society of Gynecological Oncology. Immunohistochemically, the polyps were positive for CK, partially positive for CEA, and negative for p53, calretinin, CD10, and ER. Mesonephric hyperplasia lesions were negative for all markers. The 12 pathologists did not reach a consensus, but the final diagnosis was adenocarcinoma of the uterine isthmus with mesonephric hyperplasia, which was difficult to classify. We administered additional chemotherapy, and the patient has not developed recurrence for three years postoperatively.
