Psoriasis is a chronic, inflammatory, immune-mediated, multisystem disease with a prevalence of approximately 1–3% worldwide. Chronic stable plaque psoriasis, or psoriasis vulgaris, is the most common form of the disease, accounting for 85–90% of cases. Joint involvement is common, affecting approximately 6–42% of patients with psoriasis [1]. At present, there is no curative therapy available and the clinical course is typically that of a chronically remitting and relapsing disease with well circumscribed, erythematous, indurated plaques with scale. Topical therapies constitute the first-line treatment for mild-to-moderate skin disease, and are associated with minimal adverse events such as skin atrophy, striae, tachyphylaxis, and steroid allergy. For more severe and extensive disease, photochemotherapy (psoralen plus ultraviolet A [PUVA]), broad-band or narrow-band UVB therapies, and orally administered drugs such as methotrexate, acitretin, and cyclosporine are standard [1,2]. Systemic drugs such as methotrexate, acitretin, and cyclosporine are often associated with the risks of long-term toxicity, intolerance, and lack of efficacy [2]. Despite these risks, in the past, these therapies were all that was available for treating extensive disease.