Content area
Full Text
Psoriasis is a chronic inflammatory skin disease of unknown etiology. In Japan, the estimated prevalence of psoriasis is 0.1-0.2% of the population; this is much lower than that in Western populations (2-3%). Most of the psoriasis that occurs in Japanese patients is psoriasis vulgaris. This is followed by psoriasis guttata, psoriasis arthropathica, psoriatic erythroderma, and generalized pustular psoriasis. Childhood psoriasis, including napkin psoriasis, is rare. Recently, the number of patients with psoriasis arthropathica has increased, rising to approximately 3-4% of Japanese psoriasis cases. The treatment options are poor in Japan, with no anthralin, tazarotene, acitretin, fumaric acid esters, or alefacept. Methotrexate is also not currently approved for the treatment of patients with psoriasis in Japan. Conventional therapies include topical agents (glucocorticoids and active vitamin D[sub]3[/sub] agents), ultraviolet (UV) radiation therapies (commonly psoralen combined with UVA, and narrowband UVB), and systemic treatments (etretinate and cyclosporine). Recently, the biological agents adalimumab, infliximab, and ustekinumab have been approved in Japan, and have been found to have remarkable clinical efficacy. Adv Psor Inflamm Skin Dis 2011;2(4):126-32.
Psoriasis is a chronic inflammatory skin disease of unknown etiology. The disease is inherited as a polygenic trait and is characterized by epidermal hyperproliferation, reduced epidermal turnover time with defective keratinization, and marked inflammatory cell infiltrates. Psoriasis usually requires lifelong treatment, and has been linked to various clinical manifestations of atherosclerosis including heart attack, cerebrovascular events, and peripheral vascular disease.
Psoriasis is driven and maintained by multiple components of the immune system. Although the disease has long been assumed to be a T helper type 1 cell (Th1)-mediated disorder, recent evidence indicates that tumor necrosis factor-α (TNF-α), inducible nitric oxide synthase (iNOS)-producing dendritic cells (TIP-DCs), and Th17 cells play an essential role in its pathophysiology [1,2]. This is highlighted by the remarkable clinical efficacy of anti-TNF agents and anti-interleukin-12 (anti-IL-12)/anti-IL-23-p40 antibodies for treating psoriasis [3-5]. A significant role for plasmacytoid DCs has also been proposed, which may explain the paradoxical side-effects of the anti-TNF agents [6,7].
This article will describe the characteristics of psoriasis in Japanese patients and provide an overview of the management of the disease in this population.
The prevalence of psoriasis in Japanese patients
Precise data on the prevalence of psoriasis in the Japanese population are not available....