Aim: Pediatric sarcomas are heterogeneous musculoskeletal malignancies arising from mesenchymal cells and account for less than 10% of childhood malignancies. There is limited literature on the role of 18F-Fluorodeoxyglucose Positron Emission Tomography / Computed Tomography (18F-FDG PET/CT) in the initial evaluation of pediatric sarcomas. In this retrospective analysis, we aimed to evaluate the role of 18F-FDG PET/CT for initial staging and treatment planning of sarcomas in the pediatric population.
Methods: We retrospectively analysed patient data from the PET/CT registry at our tertiary care hospital from 2010 to 2022. One hundred and seven biopsy-proven pediatric sarcoma patients underwent 18F-FDG PET/CT for initial workup. All patients fasted for four hours before radiotracer injection. Whole-body PET/CT was done 60 minutes after intravenous injection of 18F-FDG. Scan findings were reviewed qualitatively and semi-quantitatively by an experienced nuclear medicine physician. Lesions with 18F-FDG avidity and corresponding changes on CT images were designated PET-positive. The final diagnosis and change in treatment plan were evaluated based on PET/CT images.
Results: 107 children (34 female) aged 13.2±4.6 (range 1.2-19) years underwent 18F-FDG PET/CT for initial staging of sarcomas. Of these, 21/107 (19.6%) were extraosseous and 86/107 (80.4%) were of osseous origin, mainly comprising Ewing’s sarcoma, osteosarcoma, rhabdomyosarcoma and chondrosarcoma. The maximum standardised uptake value (SUVmax) of the primary lesions was 8.1±4.9 (range 1-32). Sixty–two (62/107; 57.9%) children had metastatic lesions at the initial staging workup. While 27 patients had only regional lymph node metastasis, the remaining 35 had distant metastases in either lymph nodes (17), lungs (22) or skeletal or marrow lesions (18). 18F-FDG PET/CT changed the treatment plan in 35 children who had distant metastatic lesions.
Conclusion: 18F-FDG PET/CT is a good imaging modality for accurately staging sarcomas in children and to detect distant metastases at the initial workup.