Abstract
PURPOSE: Ovarian mature cystic teratoma (MCT) is the most common ovarian tumor, and only a small fraction undergoes malignant transformation. The most prevalent malignant type of the ovary is squamous cell carcinoma, followed by adenocarcinoma. However, ruptured ovarian mature cystic teratoma with adenocarcinoma transformation is extremely rare. CASE PRESENTATION: A 75-year-old postmenopausal woman presented to the emergency room with abdominal pain following a CT examination, the patient was diagnosed with a ruptured ovarian MCT. Subsequently, surgery was performed. Finally, she was diagnosed with adenocarcinoma tumor originating from the MCT of the ovary based on histopathology and immunohistochemistry examination. Following six cycles of chemotherapy with carboplatin and paclitaxel, the patient underwent long-term follow-up, during which no recurrence was observed over 10 months of examinations. CONCLUSION: The cases of ruptured cystic teratomas are rare, and ruptured cancerous transformation in MCT is infrequently documented in the literature. Therefore, special attention should be paid when encountering such cases in medical practice, as they can easily be misdiagnosed as benign ovarian tumors.