PDE4A and discoid lupus erythematosus: Non-selective PDE4 inhibitors have no known benefit for psoriasis but selective PDE4 inhibitors have found application in the treatment of various dermatologic inflammatory conditions, including but not limited to psoriasis, cutaneous sarcoidosis, discoid lupus erythematosus, scleroderma, Behcet’s disease, and atopic dermatitis [10,14].