Spatiotemporal Evolution of Radiation Myositis on 18F-FDG PET/CT Following Hypofractionated Radiotherapy of Intramuscular Melanoma Metastases.

Radiation myositis is an infrequent late adverse effect of radiotherapy (RT), more commonly seen after hypofractionated regimens. We present the case of a 52-year-old woman with oligorecurrent metastatic melanoma who, several months after receiving local hypofractionated RT, developed a painful swelling at the irradiated site. As an integral part of routine oncologic follow-up, 18F-FDG PET/CT allowed accurate visualization of the affected region and when matched with RT treatment plans clearly illustrated their apparent overlap. This case demonstrates the utility of 18F-FDG PET/CT in the early detection and monitoring of radiation myositis and highlights the importance of a multidisciplinary approach in melanoma care.