Unexpected diagnosis of stage IIA dysgerminoma in streak gonad in a patient with Swyer syndrome: a case report.

Patients with Swyer syndrome, which is also known as 46,XY pure gonadal dysgenesis, are at an increased risk of gonadoblastoma and germ cell tumor. Prophylactic gonadectomy is recommended for these patients. We report a case of stage IIA dysgerminoma arising in a streak gonad in a patient with Swyer syndrome, which was not diagnosable preoperatively and intraoperatively. The patient was primarily amenorrheic and identified as female phenotypically. She underwent gonadectomy at 27 years of age. Preoperative image analysis showed a relatively small uterus without adnexal masses. Laparoscopic findings showed bilateral streak gonads. Postoperatively, histopathological examination revealed that the patient had dysgerminoma in her left streak gonad. Preoperative and intraoperative diagnosis of dysgerminoma in normal size ovaries is thought to be difficult. Although it is rare, considering the occurrence of dysgerminoma in streak gonad with extension to the mesosalpinx, prompt prophylactic gonadectomy is strongly recommended for these patients regardless of the size of the ovaries.