A 24-year-old woman presented to hospital with severe abdominal pain secondary to a ruptured 17cm left ovarian cyst. Histopathological evaluation of the cyst showed a 12x10mm focus of follicular variant papillary thyroid carcinoma (PTC) arising from a mature cystic teratoma with no evidence of struma ovarii. CT staging did not demonstrate distant metastases, but laparoscopic staging was undertaken to exclude peritoneal seeding. Omental biopsy showed a 1mm nodule with microclusters of PTC measuring 0.2mm and <0.1mm. BRAF staining was negative. She subsequently underwent a total thyroidectomy which confirmed the absence of PTC in the thyroid gland. Postoperative thyroglobulin was undetectable. A 5.6 GBq dose of I 131 was administered after thyroxine withdrawal, in view of the omental micrometastases. Right ovarian tissue cryopreservation was performed prior to radioactive iodine for fertility preservation. Her post treatment course was complicated by a right tubo-ovarian abscess which responded well to antibiotics. Thyroglobulin levels have remained undetectable throughout and there has been no evidence of cancer recurrence at 12 months.
Metastatic PTC arising from the ovarian teratomas is rare and evidence to support treatment options is scarce.1 Our case illustrates that PTC can be present without struma ovarii and highlights the utility of laparoscopic staging when investigating micrometastases following intraperitoneal rupture of ovarian cysts. Furthermore, concurrent pelvic infections can complicate assessment of response to therapy. Guidelines to standardise management of ovarian PTC would be beneficial.