In addition, the treatment of moderate-to-severe psoriasis shares further common features with the treatment of atopic dermatitis, such as the use of PDE4 inhibitors like apremilast, which is only approved for psoriasis in Europe, and crisaborole, which is only approved for atopic dermatitis in Europe [298], as well as JAK inhibitors [299] and various immunosuppressants [300,301]. Here, PDE4A is linked to psoriasis.