A Recurrent Mucinous Neoplasm Originating From an Ovarian Mucinous Cystadenoma After an Adnexectomy As the First Procedure: A Case Report.

Ovarian mucinous cystadenomas are benign, but they can rarely recur if incompletely excised. We are the very first to report a case of recurrent mucinous neoplasm originating from an ovarian mucinous cystadenoma after adnexectomy as the first procedure. A 58-year-old woman was referred to our hospital with a two-year history of abdominal fullness. Magnetic resonance imaging (MRI) demonstrated a pelvi-abdominal cyst measuring 37 cm, without solid components within the cyst. A laparotomy revealed a huge cystic tumor originating from the right ovary. A right adnexectomy was performed without intraoperative cyst rupture or spillage. Histologically, the cyst was diagnosed as a mucinous cystadenoma. A month after the operation, ultrasonography revealed a cystic lesion measuring 1.8 cm adjacent to the right side of the uterine body. During the follow-up every three months, the cyst enlarged gradually, and an MRI performed 42 months after the operation revealed a cystic mass measuring 5.5 cm, including an internal protrusion. The second laparotomy revealed a cystic mass arising from the right surface of the uterine body, and a total hysterectomy and left adnexectomy were performed. Histologically, this uterine tumor was diagnosed as a mucinous borderline tumor that recurred from the ovarian mucinous cystadenoma. On histological examination of the resected uterus, the silken threads used at the first operation were observed in proximity to the tumor lesion. We speculated that the reason for the recurrence of our case may be the uterine-side remanence of the mucinous tumor cells from the first operation. Because the utero-ovarian ligament became short due to the large ovarian cyst, adnexectomy as a first procedure may be insufficient. A close follow-up of these patients is required for early detection of the recurrence, and attention is necessary for patients having malignant transformation due to an adenoma-borderline-malignant sequence of ovarian mucinous tumors.