Clinicopathologic features of recurrent dysembryoplastic neuroepithelial tumor and rare malignant transformation: a report of 5 cases and review of the literature.

Dysembryoplastic neuroepithelial tumors (DNETs) have traditionally been viewed as benign "quasihamartomatous" tumors widely considered curable with surgery alone. More recently, case reports have described malignant gliomas arising after irradiation and recurrences following subtotal or even gross total resection. Herein, we describe five cases of DNET with recurrences 2-7 years after resection. Although the radiology was often alarming (e.g., new ring enhancing mass), the pathology remained benign in most cases. Nonetheless, a probably radiation induced anaplastic astrocytoma was encountered in one case 7 years after therapy. These findings suggest that these patients may need closer follow-up than initially suggested, lending further support to the notion that this tumor behaves more like a benign neoplasm, rather than a dysplastic or hamartomatous lesion.