Endocrine Abstracts

Introduction: Mature cystic teratoma is the most common germ cell tumor of the ovary and is known to be benign tumors containing well-differentiated cells from three germ layers. However, malignant transformation of the various tissue components within mature ovarian teratomas, such as the occurrence of papillary thyroid carcinoma, is extremely rare.

Case Report: During a check-up, a 62-year-old asymptomatic woman, was found to have a 5-cm hyperechoic lesion with an internal cystic component in her left ovary, suspected to be a mature teratoma. Consequently, a total hysterectomy with bilateral salpingo-oophorectomy was performed, during which an unruptured thin-walled ovarian tumor was removed. Gross pathology revealed an uniloculated solid-cystic lesion with smooth serosa. The solid part showed homogenous soft tan appearance with hair. There was no ascites or papillary projection adhesion between tumor, omentum, and uterus. The pathology report showed a 2-cm classic subtype papillary thyroid carcinoma arising in a 4.7-cm mature teratoma, without lymphovascular invasion and no involvement of the ovarian surface. Her thyroid ultrasound and thyroid function tests were normal. There was no evidence of metastasis on imaging. The role for a total thyroidectomy and radioactive iodine ablation was discussed. After reviewing the pathology and confirming the absence of aggressive behavior in the papillary thyroid carcinoma, shared decision-making was made not to pursue further management. Following a one-year follow-up, there was no recurrence or metastasis of the tumor.

Conclusions: We presented a case report describing the rare occurrence of incidentally discovered papillary thyroid carcinoma arising in a mature ovarian teratoma. Currently, there is a lack of consensus on postoperative management. After a careful evaluation to determine the aggressive behavior of the ovarian tumor and to exclude metastasis, the option of not undergoing thyroidectomy and radioactive iodine ablation may be considered.