Definition and Significance of Osseous Involvement in Newly Diagnosed Pediatric Hodgkin Lymphoma

Purpose: The Children's Oncology Group (COG) lacks a definition for osseous involvement of HL in their protocols. In the EURO-NET PHL-C1 study osseous involvement is any biopsy proven lesion, positive bony window on CT scan, positive bone scan Tc99 only if confirmed by PET or MRI, and positive on MRI if positive in bone and adjacent soft tissue. This review aims to propose a universally acceptable definition in order to move towards harmonization of staging and response criteria in pediatric HL.

Methods: We performed a comprehensive literature search through PubMed and Google scholar. Search terms included Hodgkin lymphoma, osseous lesions, bony involvement, and pediatric. Literature found included case reports, retrospective analyses, and literature reviews. Each paper was evaluated for design type, number of participants, median age at diagnosis, age range at diagnosis, percent of pediatric patients, definition of criteria of interest, diagnostic tools, study objectives, and level of evidence.

Results: 17 papers specifically addressing osseous HL were reviewed and 13 included patients in the pediatric age range (0 – 21 years). 8 were case reports with reviews of the literature; the rest were observational cohort studies. All varied in their definition of osseous involvement and diagnostic tools used ranging from biopsy to the concurrent use of multiple diagnostic images. Survival data of patients with osseous HL was comparable to those without bony involvement.

Conclusion: There is no consensus on the definition of osseous involvement in HL. Prognostically, it does not appear to have an adverse effect on outcomes with multi-modality therapy. For these reasons, we propose the use of the Euro-Net criteria, which offers a reasonable and reproducible means for the evaluation of osseous involvement of HL.