Huge mucinous borderline ovarian cystadenoma in a premenarchal girl

Epithelial ovarian tumors are common in adult women, but rare in children. Especially mucinous ovarian cystadenoma is extremely rare, with only 16 cases in premenarchal girls reported to date. We present a case of 12-year-old premenarchal girl with symptoms of lower abdominal distension. CT showed a large multilocular tumor spreading throughout the entire abdominal cavity from the right upper quadrant to the pelvic cavity. The tumor was brought out little by little with aspiration of the fluid contents with a small incision. The tumor was found to originate from the left ovary, and oophorectomy was performed. The tumor measured 26 × 18 cm and weighed 5860 g. Histological diagnosis was mucinous ovarian cystadenoma with borderline malignancy. No evidence of recurrence had been seen as of 2 years postoperatively. In the review of premenarchal mucinous borderline ovarian cystadenoma, all cases were stage I and underwent salpingo-oophorectomy or oophorectomy. Those patients were alive without recurrence. Although mucinous borderline ovarian cystadenoma was characterized as malignancy, premenarchal cases showed favorable outcomes and salpingo-oohprectomy or oophorectomy appears appropriate.