Radiologic response to radiation therapy concurrent with temozolomide for progressive simple dysembryoplastic neuroepithelial tumor.

Dysembryoplastic neuroepithelial tumors (DNETs) are low-grade neuroglial tumors that are traditionally considered to be benign hamartoma-like mass lesions. Malignant transformation and disease progression have been reported in complex DNETs. We report a case of a simple DNET with disease progression following subtotal resection. A 34-year-old woman underwent craniotomy with subtotal resection of a large nonenhancing right temporal lobe and insular mass. Histopathological analysis revealed a simple DNET. Magnetic resonance imaging obtained 6 months after surgery demonstrated disease progression with no enhancement or change in signal characteristics. Following concurrent therapy with temozolomide and external beam radiation therapy, a significant radiologic response was observed. Progressive DNET with malignant transformation exhibits predominantly glial transformation and occurs predominantly in complex DNETs. The histological classification of DNETs into simple, complex, and nonspecific are reviewed. Contrast-enhancing regions are more frequently seen in complex tumors, with nonenhancing regions having fewer complex histologic features. Close clinical and radiographic follow-up is important in all cases of DNET. Following tumor progression, radiation therapy with concurrent and adjuvant temozolomide chemotherapy may be an effective treatment.