Radiation-induced cutaneous squamous cell carcinoma showing a significant response to pembrolizumab: A case report.

Cutaneous squamous cell carcinoma (cSCC) arising from radiation dermatitis has a higher risk of metastasis than conventional cSCC. Immunosuppression is another risk factor for cSCC, suggesting that mycosis fungoides (MF) could be a risk factor for cSCC. Here we report a case of radiation-induced cSCC with a high level of tumor-mutation burden that developed in a patient with MF who was successfully treated with pembrolizumab. The present case suggests that pembrolizumab might be an optimal therapy for radiation-induced cSCC, even at advanced stages.