Glioblastoma Arising in an Immature Teratoma: A Rare Somatic Malignancy in a Germ Cell Tumor

Mature cystic teratomas constitute the most common ovarian neoplasm occurring in childhood. All the components present in mature cystic teratoma are, by definition, mature. Immature teratomas, on the other hand, are malignant, and they constitute a mixture of embryonal and adult tissues derived from all three germ layers. Commonly, the main component is neuroepithelium. The treatment of immature teratoma is surgery and multidrug chemotherapy for grade 2 and 3 tumours. Sometimes only mature components persist in metastatic sites, which may continue to grow (growing teratoma syndrome) following chemotherapy. Emergence of benign or malignant neoplasm with somatic-type features is an uncommon event in mature cystic teratomas. The most common malignant change is squamous cell carcinoma, followed by carcinoid tumour and adenocarcinoma. Other types include melanomas, sarcomas of various types, carcinosarcomas, glioblastoma, etc. Glioblastomas are among extremely rare somatic malignancies arising from mature or immature teratomas. Their etiology is not well understood, and it is still a matter of research whether they share the same genetic alteration as the tumours occurring in the central nervous system. We present a rare case of glioblastoma arising in an immature teratoma in a young female in her early 20s.