1. Department of Pediatric Surgery, Keio University School of Medicine, Tokyo 160-8582, Japan
2. Department of Pediatric Surgery, National Center for Child Health and Development, Tokyo 157-8535, Japan
3. Department of Pediatric Surgery, National Hospital Organization Saitama National Hospital, Saitama 351-0102, Japan
4. Department of Surgery, Tokyo Metropolitan Children’s Medical Center, Tokyo 183-8561, Japan
5. Department of Pediatric Surgery, Tokai University School of Medicine, Kanagawa 259-1193, Japan
6. Department of Pathology, National Center for Child Health and Development, Tokyo 157-8535, Japan
7. Kanagawa Children’s Medical Center, Yokohama 232-0066, Japan