CT, MRI, and FDG PET/CT in the Assessment of Lymph Node Involvement in Pediatric Hodgkin Lymphoma: An Expert Consensus Definition by an International Collaboration on Staging Evaluation and Response Criteria Harmonization for Children, Adolescent, and Young Adult Hodgkin Lymphoma (SEARCH for CAYAHL)

Staging of pediatric Hodgkin lymphoma is currently based on the Ann Arbor classification, incorporating the Cotswold modifications and the Lugano classification. The Cotswold modifications provide guidelines for the use of CT and MRI. The Lugano classification emphasizes the importance of CT and PET/CT in evaluating both Hodgkin lymphoma and non-Hodgkin lymphoma but focuses on adult patients. This article presents consensus guidelines that extend the traditional classifications used for adult Hodgkin lymphoma staging and provide rigorous definitions of lymph node groups based on MRI, CT, and fluorodeoxyglucose PET/CT findings. This allows consistent terminology and definitions, using metabolic and morphologic imaging to identify affected lymph nodes or extranodal regions and organs. The pattern of involvement, together with other individual risk factors, determines treatment strategy. In case of inadequate response to chemotherapy, radiation therapy is often required. Standardization of staging definitions for pediatric Hodgkin lymphoma is necessary for comparing treatment outcomes between North American and European clinical trials and a prerequisite for clear communication during tumor boards and central review. This comprehensive imaging atlas is intended to provide regional criteria for nodal involvement and to serve as a standardized guide for the anatomic assignment of lymph node involvement in pediatric Hodgkin lymphoma.