18F-FDG PET/CT findings of paratesticular alveolar rhabdomyosarcoma

Rhabdomyosarcoma (RMS) originates from primitive mesenchymal cells and is the most common soft tissue tumor in childhood. ¹⁸F-fluoro-deoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography (CT) has been reported to be valuable in RMS staging and risk stratification. Paratesticular RMS is a relatively uncommon form of RMS, most of which are of the embryonal histologic type. Paratesticular alveolar RMS is associated with aggressive behavior, high metastatic potential, and poor outcomes. To the best of our knowledge, ¹⁸F-FDG PET/CT imaging findings of paratesticular alveolar RMS have never been described. Here, we report on a 16-year-old boy's rare paratesticular alveolar RMS with multiple metastases and its findings on ¹⁸F-FDG PET/CT. This case also demonstrates the potential value of ¹⁸F-FDG PET/CT in RMS staging and treatment decisions, and may aid in the differential diagnosis.