Staging of Waldeyer’s ring in Pediatric and Adolescent Patients with Hodgkin’s lymphoma – Importance of multimodality imaging

Introduction Compared to pediatric Non-Hodgkin’s lymphoma, involvement of Waldeyer’s ring (IOWR) is rare in pediatric Hodgkin’s lymphoma (HL). The decision on IOWR is based on ENT inspection. This method was included into the staging algorithm more than 30 years ago when modern cross-sectional imaging techniques were not as sophisticated as they are nowadays. ENT inspection can only evaluate the mucosal surface and is prone to interobserver variability. We hypothesize that combined morphologic and metabolic image reading results in a more accurate staging of the Waldeyer’s ring (WR).

Methods The EuroNet-PHL-C1 trial recruited 2102 patients. 14 of them were diagnosed to have an IOWR and fulfilled the three inclusion criteria 1) central review was performed, 2) sufficiently evaluable imaging data (18F-FDG-PET, CT or MR) were available and 3) IOWR was diagnosed with ENT examination. The WR of these 14 patients was re-evaluated by applying an image-based algorithm consisting of 18F-FDG-PET and CT or MR (F18-FDG-PET worked as gate keeper by detecting asymmetric glucose metabolism in the WR region; then CT/MR evaluated the underlying reason for the asymmetric glucose metabolism). This algorithm was also applied to 100 consecutive patients who fulfilled the above mentioned criteria 1) and 2), but whose WR was inconspicuous on ENT examination.

Results The image-based algorithm confirmed only four of the 14 patients with IOWR on ENT examination. Of the remaining 10 patients, four had involvement of a retropharyngeal lymph node by HL but an inconspicuous WR and six had a completely inconspicuous WR on imaging. Applied to 100 consecutive patients with inconspicuous WR on ENT examination, the image-based algorithm confirmed non-involvement in 99 patients. Suspicion of IOWR was raised in one patient.

Conclusion The application of an image-based algorithm is feasible and easily applicable. It may subsitute ENT investigation in future study protocols and may also have an influence on the number or/and on the extension of irradiation fields of the upper neck in HL patients.