Dr. Arnold received a B.A. in molecular genetics from the University of Rochester (Rochester, NY), and completed the medical scientist training program at the University of Texas Southwestern Medical Center at Dallas, receiving his Ph.D. in Genetics and Development for his work in the laboratory of Dr. Eric N. Olson. He completed residency training in Anatomic Pathology at the University of Texas Southwestern Medical Center at Dallas and the National Cancer Institute at the National Institutes of Health. While at the National Cancer Institute, he completed a research fellowship in ultrastructural pathology and pediatric tumor pathology with Dr. Maria Tsokos. Following his research fellowship, Dr. Arnold Nationwide Children’s Hospital where he completed a pediatric pathology fellowship. He became a faculty member at The Ohio State University and practiced at Nationwide Children’s Hospital as a staff pathologist later becoming Director of Surgical Pathology. He subsequently moved to Children’s Hospital Colorado in 2019 to become the Medical Director of Anatomic Pathology, and is also currently the Pathology Informaticist for Children’s Hospital Colorado.