Adenocarcinoma arising from the respiratory ciliated epithelium in a benign cystic teratoma of the ovary

Benign cystic teratoma of the ovary (BCTO) is the most common benign ovarian tumor, accounting for 15–20% of all ovarian tumors. It is usually diagnosed in the third and fourth decades of life. Malignant transformation is rare, occurring in approximately 1–2% of reported cases, with squamous cell carcinoma being the most common form. Adenocarcinoma arising from mature cystic teratoma is extremely rare. We present the patient with a BCTO, where a malignant transformation of respiratory ciliated epithelium resulted in well differentiated adenocarcinoma. Although respiratory epithelium is often found in BCTOs, adenocarcinoma arising from this cell type is uncommon. To our knowledge, this is the fourth reported case of adenocarcinoma arising from the respiratory epithelium of a BCTO.