Malignant transformation of DNETs: a case report and literature review.

Dysembryoplastic neuroepithelial tumors (DNETs) have traditionally been thought of as lesions with a benign clinical course that generally do not undergo malignant transformation. However, cases are emerging of DNETs that progress to more malignant forms. We present a case of malignant transformation, and we compile and review all previously published cases to identify common characteristics that may confer a higher risk for malignant transformation. A PubMed search was performed of all English-language case reports of DNET transformations to malignant cancers. The demographic, clinical, and histologic features of these patients are compiled and analyzed. A separate case report with histologic descriptions is also presented. A total of 10 case reports of DNET malignant transformation were found. The majority of cases involved complex-type DNETs. A higher proportion of extratemporal lesions were observed. Almost all cases involved subtotal resection. Risk factors for malignant progression of DNET lesions include complex-type histologic features, extratemporal location, and subtotal resection. Malignant dedifferentiation of astrocytic or oligodendrocytic cells within the glial nodule of complex DNETs may be the source of these transformations. There are no radiographic features that differentiate DNETs that are at higher risk for transformation.