PDCD1 and skin squamous cell carcinoma: A 64-year- old woman with lymphogenic metastasized CSCC of the left limb presented in our dermatological department with a three-week history of severely pruritic, coalescent, erythematous, and scaly macules and papules in sun-exposed areas of the skin (V-area of the upper trunk and neck, forearms, dorsal hands, lower legs, and dorsal feet, Figure 2A) five weeks after the administration of the anti-PD-1 antibody cemiplimab.