Giovanni Spinaci, Laurentiu Agrigoroaie, Daniel Orbach, Salma Moalla, Helene Boutroux, Federico Mercolini, Sarah Winter, Lucy Metayer, Pierre Khneisser, Hervé J Brisse, Veronique Minard-Colin, Nina Jehanno
18F-FDG PET/CT demonstrates excellent accuracy for BM staging and strong performance for nodal assessment in pediatric RMS. These findings support selective omission of invasive staging procedures in patients with negative 18F-FDG PET/CT while reinforcing the complementary role of sentinel node biopsy in specific subgroups.
BACKGROUND: Accurate staging is critical in pediatric rhabdomyosarcoma (RMS), as bone marrow (BM) and nodal involvement strongly influence risk stratification and treatment. Current guidelines recommend invasive procedures, including bone marrow aspirate/biopsy (BMAB) for all patients, and nodal histology in selected patients, despite their burden in children. This study evaluates the diagnostic performance of 18F-FDG PET/CT for BM and nodal staging in pediatric RMS.
METHODS: A retrospective, multicenter study was conducted including patients less than 25 years with newly diagnosed RMS from Paris Kids Cancer centers who underwent baseline 18F-FDG PET/CT. PET/CT accuracy was assessed using BMAB as the reference standard. For nodal staging, histological confirmation was used when available; otherwise, an exploratory real-world clinical assessment of lymph node status based on imaging and follow-up was applied. Discordant cases underwent multidisciplinary review including MRI.
RESULTS: Among 147 patients, 129 had both 18F-FDG PET/CT and BMAB. PET/CT correctly classified BM status in more than 99% of cases, with a negative predictive value of 99.1%. Nine PET-positive/BMAB-negative cases were confirmed as true BM involvement on MRI, reflecting possible BMAB sampling bias. For nodal staging, 18F-FDG PET/CT sensitivity and specificity were 85.2% and 85.7% versus histology (48 cases). Using real-world clinical assessment (146 cases), sensitivity and specificity increased to 86.5% and 96.8%, respectively.
CONCLUSIONS: 18F-FDG PET/CT demonstrates excellent accuracy for BM staging and strong performance for nodal assessment in pediatric RMS. These findings support selective omission of invasive staging procedures in patients with negative 18F-FDG PET/CT while reinforcing the complementary role of sentinel node biopsy in specific subgroups.