1. Department of Neurosurgery (Y.H., S.T., Y.I., T.K., A.T., A.M.), Nippon Medical School, Tokyo 113-8603, Japan
2. Department of Pathology (C.I.), Tokai University School of Medicine, Kanagawa 259-1193, Japan
3. Department of Pathology (R.Y.O.), International University of Health and Welfare, Mita Hospital, Tokyo 108-8329, Japan
4. Japan Labour Health and Welfare Organization (A.T.), Tokyo Rosai Hospital, Tokyo 143-0013, Japan