Oncocytic and tall columnar type papillary thyroid carcinoma arising on a mature cystic teratoma: A case report and literature review.

Mature cystic teratoma (MCT) is the most common germ cell ovarian tumour, which accounts for 15-20% of all ovarian neoplasms. The frequency of MCT cases undergoing malignant transformation ranges from 0.17% to 2%. Our aim for presenting this case is to contribute to formation of an algorithm in the literature for the treatment and follow-up of MCT undergoing malignant transformation. A 38-year-old female patient presented to the emergency service with acute abdomen. The patient underwent salpingo-oophorectomy due to a prediagnosis of ovarian torsion with a dermoid cyst. Postoperative pathological examination reported oncocytic and tall columnar type papillary thyroid carcinoma arising on a mature cystic teratoma. During the follow up no local recurrences or metastases were identified in one-year. The rarity of MCT cases undergoing papillary type thyroid carcinoma transformation hinders the establishment of an algorithm for treatment and follow-up in literature.