Diagnosis of struma peritonei 15 years after rupture of mature teratoma

Background: Struma peritonei is an extremely rare presentation of struma ovarii. Case: Here we report the case of a 38-year-old woman with a history of papillary thyroid cancer, left ovary struma ovarii, ruptured mature cystic teratoma of the right ovary, and endometriosis presenting with pelvic pain, dysmenorrhea, abnormal uterine bleeding, and infertility. A diagnostic laparoscopy was performed to evaluate for recurrence of endometriosis. However, multiple abnormal appearing lesions were found on her left hemidiaphragm and left abdominal wall. The tissue was identified as ectopic thyroid tissue identical to the patients ruptured mature cystic teratoma which occurred 15 years prior. A second subsequent laparoscopy was performed to excise the lesions. Eleven additional lesions were identified as ectopic thyroid tissue. This peritoneal dissemination was likely a result of tissue seeding post-mature teratoma rupture. Conclusion: Gynecologists should consider the possibility of struma peritonei in patients who have a history of papillary thyroid cancer and struma ovarii who present with significant pelvic pain and abnormal uterine bleeding.