A rare case of extraventricular neurocytoma.

We report an unusual case of extraventricular (cerebral) neurocytoma with a long, 25-year history, and which appeared to transform to neuroblastoma. In 1978, an 18-year-old woman was treated for right frontal oligodendroglioma. Eighteen years later (in 1996), recurrence of tumor in the fourth ventricle was noted and was treated with gamma-knife radiotherapy. The tumor shrunk transiently, but 7 years later (in 2004), MRI study demonstrated a second recurrence and ventricular dissemination. Partial removal was performed, and histological examination revealed that tumor cells had round or oval nuclei with halos. Frequent mitoses and vascular proliferation were observed. The MIB-1 LI was 80%. Despite postoperative whole-brain radiotherapy to a total dose of 30 Gy, the tumor progressed, and she died at 4 months after the second surgery.