Central neurocytoma, a cerebral intraventricular tumor, is usually benign. It frequently develops in the area of the foramen of Monro, and is usually attached to the septum pellucidum. Mild to moderate contrast enhancement is common. We encountered a case of central neurocytoma in a 60-year-old woman; the tumor arose from the atrium of the lateral ventricle, and extraventricular extension and malignant transformation were apparent. CT and MRI revealed a well-defined, slightly heterogeneous mass measuring 2.5x3x5cm with surrounding edema. There was strong contrast enhancement of the mass.