Mucinous Adenocarcinoma Transformation in Ovarian Mature Cystic Teratoma Complicating Pregnancy: A Case Report

Most adnexal masses found in pregnancy are simple benign cysts less than 5 cm in diameter. On the other hand, the majority of persistent adnexal masses 5 cm or greater in diameter are mature teratomas. Malignant transformation occurs in 0.2 to 2 percent of mature teratomas, and squamous cell carcinoma arising from ectoderm is the most common secondary neoplasm. The mucinous cystadenocarcinoma transformation is very rare. We presented a 38-year-old G2Ab1 woman at 32 weeks of gestation with a huge, rapid growth adnexal mass who came to our emergency department due to severe preeclampsia, stage 1 of IUGR, and borderline AFI. After 48 hours of expectant management, a cesarean section associated with unilateral salpingo-oophorectomy was done, and the histopathology of the cyst revealed mature teratoma that was focally involved with mucinous cystadenocarcinoma. The complete surgical staging was done, and due to the stage of disease (1C1), she received adjuvant chemotherapy, and she has remained disease-free in her last follow up after one year.