Behçet's disease: review with emphasis on dermatological aspects.

Behçet's disease is a systemic vasculitis characterized by attacks of acute inflammation, which can affect almost every vascularized area of the body. There is a close correlation between the geographical distribution of HLA-B51 and its prevalence. In the etiopathogenesis there are indications of genetic susceptibility associated with environmental influence. Among the involved genes are those that encompass innate and adaptive immunities. Polymorphisms and epistatic interactions in several genes are described, as well as the presence of imbalance lineage between HLA-B51 and A (MICA). Herpes simplex and Streptococcus sanguinis may be important extrinsic factors. An increase of Th1 response and of IL-21 is observed. The production of IL-21 is positively related to Th17 cells and negatively to T-regs. The mucocutaneous manifestations are Behcet´s disease markers, and their earlier onset indicates a worse prognosis. Recurrent oral ulcers have varied sizes and arrangements, genital ulcers are recurrent, leaving scars, skin lesions are multivaried, and pathergy, although not so frequent, is important for the diagnosis. There are numerous attempts to validate indexes that can evaluate the disease activity and among them the Mucocutaneous Activity Index. This is a specific score that can help with therapeutic decisions and to reduce morbidity, but still lacks validation. The clinical manifestations of other organs are described as well as treatment options.