Malignant transformation of a mature cystic teratoma of the ovary with rupture.

Malignant transformation or tumor rupture is a rare complication of ovarian mature cystic teratomas. We present computed tomography (CT) images of a 52-year-old woman that revealed a large, predominantly cystic mass filled with fat and enhanced solid components located in the lower abdomen. Ten days later, the cystic mass ruptured, and massive ascites was observed on magnetic resonance imaging (MRI). Resulting from the rupture, MRI revealed reduced size and thickening wall of the tumor. After resection, the mass ruptured, and malignant transformation (squamous cell carcinoma) was observed. To our knowledge, there are no reports describing before and after images of a ruptured cystic teratoma with malignant transformation.