1. Department of Pediatrics School of Medicine University of Yamanashi Chuo Yamanashi Japan
2. Department of Pathology School of Medicine University of Yamanashi Chuo Yamanashi Japan
3. Department of Diagnostic Pathology National Cancer Center Hospital Chuo‐ku Tokyo Japan
4. Rare Cancer Center National Cancer Center Hospital Chuo‐ku Tokyo Japan
5. Department of Pediatric Oncology National Cancer Center Hospital Chuo‐ku Tokyo Japan
6. Department of Musculoskeletal Oncology National Cancer Center Hospital Chuo‐ku Tokyo Japan