TMB and clinical signs of sun exposure. Photographs of the observable clinical signs of sun damage surrounding the scars of primary melanoma excision of four patients: (A) melanoma of the external side of the right foot; TMB 2 muts/Mb DNA; progression disease at 6-month follow-up, (B) melanoma of posterior side of the right calf; TMB 1 mut/Mb DNA; progression disease at 6-month follow-up, (C) melanoma of the upper back; TMB 45 muts/Mb; complete response at 6-month follow-up, and (D) melanoma of the posterior part of the neck; TMB 44 muts/Mb DNA; complete response at 6-month follow-up. Absence of sun-damaged skin (*). Sun-induced freckling (black arrow). muts/Mb, mutations per megabases; TMB, tumor mutational burden.