Division of Endocrinology Fellowship | Leadership
Program Leadership

Ari J. Wassner is Director of the Endocrinology Fellowship Training Program at Boston Children’s Hospital. He earned his MD from Harvard Medical School and completed residency in Pediatrics at Boston Children’s Hospital, where he also served as Chief Resident. He completed fellowship in Pediatric Endocrinology at Boston Children’s Hospital. Dr. Wassner is a member of the Boston Children’s Hospital Graduate Medical Committee and the teaching Academy at Harvard Medical School. In addition to resident and fellow education, he participates in preclinical medical education and curriculum development at Harvard Medical School, for which he has received the 2017 Masland Award and the 2023 Donald O’Hara Faculty Prize for Excellence in Teaching. In addition to practice in general endocrinology and in the joint Endocrine Oncology clinic with the Dana-Farber Cancer Institute, Dr. Wassner is Medical Director of the Thyroid Center at Boston Children’s Hospital, where he cares for children with thyroid nodules, thyroid cancer, and other complex thyroid disorders. His basic research has investigated the role of thyroid hormone metabolism in modulating local and systemic thyroid hormone signaling in disease states including heart failure and liver injury. Currently, Dr. Wassner’s clinical research focuses on pediatric thyroid disease, particularly thyroid neoplasia in children.

Jessica L. Ruiz is Associate Director of the Endocrinology Fellowship Training Program at Boston Children’s Hospital. She completed undergraduate studies in bioengineering at Rice University and earned her MD from Harvard Medical School in the Harvard-MIT Health Sciences and Technology (HST) Program. She completed residency training in Pediatrics in the Boston Combined Residency Program, followed by fellowship in Pediatric Endocrinology at Boston Children’s Hospital. Dr. Ruiz’s research uses continuous glucose monitoring and machine learning to create predictive models for dysglycemia in children with or at risk of diabetes. She is also interested in the inpatient management of dysglycemia and incorporating the use of diabetes technology in the hospital setting. She has been recognized on the Fellow Teaching Honor Roll, is on the board of student advisors for the HMS HST program, and enjoys precepting and mentoring trainees.

Lynne Mills-Fawzy is the Program Coordinator for the Endocrinology Fellowship Training Program at Boston Children’s Hospital. She started her career in medical education in the Department of Pediatrics as part of the Boston Combined Residency Program at Boston Children’s Hospital. She is involved in the Graduate Medical Education Office and is a member of the GME Wellness Sub-committee. Lynne has worked at Boston Children’s Hospital for over ten years.