Atypical Teratoid Rhabdoid Tumor Diagnosis after Partial Resection of Dysembryoplastic Neuroepithelial Tumor: Case Report and Review of the Literature.

Dysembryoplastic neuroepithelial tumors (DNETs) are generally considered benign, slow-growing epilepsy-associated lesions. While rare cases of malignant transformation of DNET to high-grade glial tumors have been reported, to our knowledge there have been no reports of transformation/emergence of DNET to atypical teratoid rhabdoid tumor (AT/RT), a highly aggressive embryonal brain tumor. Here, we report the case of an 8-year-old boy who presented with an incidental finding of a small right insular lesion which grew slowly over 3 years. The patient first underwent surgery with subtotal tumor resection at age 11. Pathology was consistent with DNET. Following surgery, further tumor growth was evident, requiring fractionated radiotherapy and eventually chemotherapy, but continued tumor growth was witnessed. Three years after radiation, imaging showed dramatic further tumor growth, and the patient underwent a second debulking surgery. The pathology revealed a malignant tumor with BAF47-negative cells, suggestive of AT/RT. This report adds to our knowledge about the poorly understood behavior and natural history of DNETs and emphasizes the importance of lifelong clinical and neuroimaging follow-up of these lesions.