Gliomatosis peritonei and ectopic decidua in pregnancy after treatment for immature teratoma

In February 2022, a 26-year-old patient was referred to our institution for evaluation of a suspected recurrent immature tera- toma. She had no significant co-morbidities and had previously given birth to a healthy male infant. Her surgical history was significant for a laparoscopic right ovarian cystectomy performed 5 years earlier for a mature teratoma. In November 2021, she un- derwent a laparotomic left salpingo-oophorectomy, omentectomy, and appendectomy for an asymptomatic 17 cm wide pelvic mass. Pre-operative tumor marker levels had not been measured, and imaging was negative for extra-ovarian disease. The final histo- pathological report was consistent with a pure immature teratoma of the ovary, grade 3, International Federation of Gynecology and Obstetrics (FIGO) stage IA.