1. Department of Surgery, the Mutual Aid Association for Teachers and Officials Sanraku Hospital, 2-5 Kandasurugadai, Chiyoda-ku, Tokyo 101-8326, Japan
2. Department of General Surgery, Kyouwa Chuo Hospital, 1676-1 Kadoi, Chikusei-shi, Ibaraki 309-1195, Japan
3. Division of Surgical Pathology, Tokyo Medical and Dental University, Tokyo, Japan