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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. [ABSTRACT FROM AUTHOR]

Nectin cell adhesion molecule 4 (nectin-4) is a transmembrane protein overexpressed on a variety of cancers and plays an important role in oncogenic and metastatic processes. The nectin-4-targeted antibody-drug conjugate enfortumab vedotin has been approved for treating locally advanced or metastatic urothelial cancer, but the efficacy in other types of cancer remains to be explored. The aim of this study was to evaluate the feasibility of nectin-4-targeted PET imaging with 68 Ga-N188 as a noninvasive method to quantify membranous nectin-4 expression in multiple tumor types-an approach that may provide insight for patient stratification and treatment selection. Methods: Sixty-two patients with 16 types of cancer underwent head-to-head 68 Ga-N188 and 18 F-FDG PET/CT imaging for initial staging or detection of recurrence and metastases. Correlation between lesion SUV max and nectin-4 expression determined by immunohistochemistry staining was analyzed in 36 of 62 patients. Results: The SUV max of 68 Ga-N188 had a positive correlation with membranous nectin-4 expression in the various tumor types tested ( r = 0.458; P = 0.005), whereas no association was observed between the SUV max and cytoplasmic nectin-4 expression. The detection rates for patient-based analysis of 68 Ga-N188 and 18 F-FDG PET/CT examinations were comparable (95.00% [57/60] vs. 93.33% [56/60]). In patients with pancreatic cancer, 68 Ga-N188 exhibited a potential advantage for detecting residual or locally recurrent tumors; this advantage may assist in clinical decision-making. Conclusion: The correlation between nectin-4-targeted 68 Ga-N188 PET imaging and membranous nectin-4 expression indicates the potential of 68 Ga-N188 as an effective tool for selecting patients who may benefit from enfortumab vedotin treatment. The PET imaging results provided evidence to explore nectin-4-targeted therapy in a variety of tumors. 68 Ga-N188 may improve the restaging of pancreatic cancer but requires further evaluation in a powered, prospective setting., (© 2024 by the Society of Nuclear Medicine and Molecular Imaging.)

Rhabdomyosarcoma (RMS) originates from primitive mesenchymal cells and is the most common soft tissue tumor in childhood. 18 F-fluoro-deoxyglucose ( 18 F-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, 18 F-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 18 F-FDG PET/CT. This case also demonstrates the potential value of 18 F-FDG PET/CT in RMS staging and treatment decisions, and may aid in the differential diagnosis., Competing Interests: The authors declare no conflict of interest., (© 2024 The Authors. Cancer Innovation published by John Wiley & Sons Ltd. on behalf of Tsinghua University Press.)