A case of ovarian mature cystic teratoma with malignant transformation to papillary thyroid carcinoma and review of the literature

We report a case of mature cystic teratoma with malignant transformation to papillary carcinoma of the thyroid gland.A 26-year-old woman (null gravida, unmarried) was referred to a physician for lower abdominal pain, and bilateral ovarian tumors were detected. On MRI, the high-signal area of the ovarian tumors disappeared with fat suppression, and bilateral mature cystic teratomas were detected. Laparoscopic bilateral ovarian tumor resection was performed. Intraoperative rupture of the ovarian cyst was observed bilaterally. Histopathological examination revealed squamous epithelium in the left ovarian tumor and an enlarged thyroid follicular-like structure with sporadic papillary structures. The follicular epithelium contained enlarged nuclei with nuclear grooves and intranuclear inclusion bodies, and a diagnosis of malignant transformation of mature cystic teratoma to papillary thyroid carcinoma was made. Considering her age and aims to reserve fertility, left salpingo-oophorectomy was additionally performed, and there was no residual tumor found in the additionally resected specimen. The postoperative staging was stage IC1 pT1cN0M0.No adjuvant chemotherapy was given. The patient has displayed no signs of recurrence for 17 months after surgery. Malignant transformation of mature cystic teratoma to papillary thyroid carcinoma is extremely rare, and there is no established treatment plan.〔Adv Obstet Gynecol, 76(1): 60-68, 2024(R6.2)〕