Uncommon tumefactions known as xanthogranulomas can occur throughout the body. Some appear to develop as benign or malignant neoplasms. An even less familiar xanthogranuloma occurs within the choroid plexus. Most are tiny plaques only a few millimeters in diameter. However, they can present as masses of significant size within the glomus. When large and unilateral, they are included in the differential diagnosis of choroid plexus tumors. A computed tomographic (CT) study of such a tumor is presented.