Yolk sac tumor of the ovary in a conjoined twin

A 5-year-old conjoined twin girl had a yolk sac tumor of the right ovary. She was admitted to our hospital because of abdominal distension. Comprehensive clinical and radiological investigations revealed a tumor of the right ovary. She underwent right salpingo-oophorectomy. The diagnosis was yolk sac tumor (stage I A), and postoperative chemotherapy (vincristine, actinomycine-D, cyclophosphamide) according to the UK-CCSG was provided. The postoperative course was uneventful with no evidence of recurrence 3 years after surgery. Her twin sister had no tumor. This is the first reported of yolk sac tumor of the ovary in a conjoined twin.