1 Cancer and Blood Disorders Institute, Johns Hopkins All Children's Hospital, Saint Petersburg, Florida, USA.
2 Division of Pathology, Johns Hopkins All Children's Hospital, Saint Petersburg, Florida, USA.
3 Sarcoma Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, USA.
4 Division of Pediatric Hematology/Oncology/Bone Marrow Transplant, Department of Pediatrics, Medical College of Wisconsin, Children's Wisconsin, Milwaukee, Wisconsin, USA.