Glioblastoma multiform in a dermoid cyst of the ovary.

Malignant transformation is reported in less than 2% of benign cystic teratomas. Although all the elements can undergo this transformation, it is most often seen in squamous epithelium. The malignancy of neural elements is probably the least common event, with only one case previously reported. A case of glioblastoma multiform in a benign cystic teratoma is presented. Its neural derivation was supported by an immunohistochemical staining specific for Glial Fibrillary Acidic Protein (GFAP). Despite very conservative surgery without adjuvant therapy, the patient remains alive and symptom free more than 3 years later.