Unexpected finding: Papillary thyroid carcinoma arising in a mature ovarian teratoma - A case report and literature review

INTRODUCTION AND IMPORTANCE: Malignant transformation within mature cystic teratomas is a rare occurrence, with an estimated risk ranging from 0.17 % to 2 %. Squamous cell carcinoma is the most common malignancy associated with this condition, while papillary thyroid carcinoma rarely presents within ovarian teratomas. This transformation predominantly affects postmenopausal women but can, albeit rarely, manifest in younger women. CASE PRESENTATION: We present a case of a 37-year-old woman who was incidentally found to have a right ovarian cyst measuring 20 × 20 × 10 mm during a cesarean section, displaying characteristic features of a teratoma. Histological examination confirmed the presence of papillary thyroid carcinoma originating within the ovarian mature cystic teratoma. Immunohistochemical analysis demonstrated positive staining for specific thyroid differentiation markers, including TTF1 and Thyroglobulin. The patient was in good health otherwise, with normal clinical and radiological evaluations of the thyroid, and no additional treatment was administered. Currently, seven years after surgery, the patient remains free of recurrence. DISCUSSION/CONCLUSION: Given the rarity of this condition, established treatment protocols are lacking, and its histogenesis remains uncertain. To advance our understanding of pathogenesis, prognosis, and therapeutic strategies for this malignant transformation, the publication of additional cases with similar presentations would be highly valuable.