Here, we report histological and molecular analyses of skin nevi from four different RTHα patients, showing that they express markers (keratin 17, type 3 deiodinase, DIO3) indicative of unbalanced, increased cellular proliferation versus differentiation, together with expression of markers that are characteristic of different subtypes (basal cell carcinoma [BCC], squamous cell carcinoma [SCC], and melanoma) of skin tumor. Here, KRT17 is linked to melanoma.