Radiation-Induced Myopathy Developing in a Hodgkin Lymphoma Patient: An Autopsy Case with Systemic Muscle Sampling

Radiation-induced myopathy (RIM) is a rare complication occurring years after radiotherapy. RIM basically occurs within the irradiation field, but some cases have been reported to be accommodated by myopathy outside the irradiation field, and the actual extent of RIM is obscure. The presented case also showed decreased MMT scores and abnormal needle electromyography results in the muscles outside the irradiated field, and the patient was initially thought to have RIM both within and outside the irradiated field. However, while systemic postmortem muscle sampling revealed prominent myopathy in line with RIM in the irradiated muscles, only mild myogenic changes that could be explained by other causes such as age-related sarcopenia, radiculopathy, and disuse atrophy were observed in the non-irradiated muscles. The number of biopsy sites in live patients is limited due to the invasive nature of the procedure, but we were privileged to systemically evaluate the extent of myopathy through multiple muscle sampling including muscles both inside and outside of the irradiation field because this was an autopsy case. Through the presented case, we conclude that RIM is a phenomenon most probably limited to the muscles within the irradiated field, and myopathy outside the irradiation is due to other causes.