Dysembryoplastic neuroepithelial tumor-like neoplasm of the septum pellucidum: A lesion often misdiagnosed as glioma - Report of 10 cases

The authors report a series of 10 low-grade neoplasms arising in the midlin e anteriorly in the region of the septum pellucidum with many of the histol ogic features of dysembryoplastic neuroepithelial tumor (DNT). The patients (five female, five male) ranged in age from 6 to 35 years (mean age, 21.5 years). The most common presenting symptoms were headache, nausea and vomit ing, and visual disturbances. Radiographically, the tumors extended into th e lateral ventricles from the septal region and obstructed the foramen of M onro. Varying degrees of hydrocephalus were present. The lesions were lobul ar, well-delineated, hypointense to brain on T1-weighted magnetic resonance imaging, and hyperintense on T2-weighted images. They were uniformly nonen hancing or showed only minimal peripheral enhancement. The tumors, in aggre gate, had the histologic features of DNT. These included a mucin-rich backg round, oligodendrocyte-like cells, "floating neurons," and a "specific glio neuronal element." Seven patients underwent gross total resection and two u nderwent subtotal resection. No patients received adjuvant chemotherapy or radiotherapy. On follow-up (n = 6; median, 14 months), all tumors had eithe r not recurred or were radiologically stable. On the basis of both neuroima ging and histopathology, DNT-like lesions should be considered in the diffe rential diagnosis of midline intraventricular tumors in children and young adults. Distinction from more aggressive neoplasms is essential because the se tumors appear to behave in a benign fashion.