Abstract
BACKGROUND: Mature cystic teratoma of the ovary is classified among the benign ovarian germ cell neoplasms, and its malignant transformation occurs very rarely (in about 2%). As a result of nonspecific signs and symptoms, preoperative diagnosis of theses malignancies is a challenge to clinicians, resulting in delayed diagnosis (in advanced stages) and poor outcomes. CASE PRESENTATION: We report the case of a 43-year-old Iranian woman with progressive distension of the abdomen and hypogastric pain, who was diagnosed with squamous cell carcinoma transformation in a mature cystic teratoma of the ovary confirmed by histopathology examination. Total abdominal hysterectomy, bilateral salpingooophorectomy, and comprehensive staging surgery were performed for the patient, and she was scheduled for chemotherapy after the surgery. She responded well to the treatment and is currently continuing her chemotherapy process. CONCLUSION: There are a great number of reports in the literature regarding mature cystic teratoma of the ovary transformation into malignancy, so these neoplasms must be considered as a possible differential diagnosis and should be evaluated in older individuals with abdominal pain and palpable mass, or those with considerable tumor diameter and raised serum tumor markers.