Ovarian choriocarcinoma as the first manifestation of 46,XY pure gonadal dysgenesis.

We report a case of 46,XY pure gonadal dysgenesis (Swyer syndrome) in a phenotypically normal 12-year-old girl with a history of vaginal bleeding and early breast development, with ovarian choriocarcinoma as the first manifestation. The clues leading to the diagnosis included the failure to establish any relationship between normal menstrual cycles postoperatively and a small remaining contralateral ovary. The correct diagnosis is important for cancer prophylaxis and hormonal replacement therapy. Prepubertal and peripubertal girls presenting with gonadal germ cell tumors should be carefully evaluated for the possibility of underlying gonadal dysgenesis. A history of vaginal bleeding or early signs of puberty does not exclude the diagnosis.