Stage Ia squamous cell carcinoma as the malignant transformation of giant and unusual mature teratoma of the ovary in an elderly patient

Background Mature cystic teratomas of the ovary (MCTO) are a type of germ cell tumor that may contain well-differentiated tissues developed from three germ cell layers and constitute about 20% of ovarian germ cell tumors. They are rare ovarian tumors with an annual incidence variable from 1.2 to 14.2 cases per 100,000 that occur mainly in women of reproductive age. They are frequently benign with a slow growth rate, even if they can undergo a malignant transformation in about 1-2% of cases. Case presentation Here, we present the case of an elderly woman referred to gynecological first aid for acute abdominal pain and showing a giant and unusual MCTO at rapid growth with malignant transformation in squamous cell carcinoma (FIGO stage Ia). The patient underwent pelvic mass removal trough emergency longitudinal midline laparotomic incision with intraoperative frozen pathologic examination. A complete surgical staging during the first surgery was performed. After about 9 years of follow-up, she died of non-oncological reasons without recurrence. Conclusions Present case highlights that CMTO with malignant transformation should always be suspected in elderly women in presence of pelvic mass at rapid growth, even if in absence of other clinical and ultrasonographic signs of malignancy. An intraoperative frozen pathologic examination may drive the best treatment.