The pathogenesis of vasculitis is not yet completely clear, but the recognized factors associated with triggering this disease include: 1, genetic factors: closely related to autoimmunity, a certain stage may appear immune metamorphosis, over-response series performance; 2, smoking: nicotine easy to cause vasospasm, inducing inflammatory reactions, the formation of micro-thrombosis and then cause vascular obstruction; 3, cold, freezing history and living in the northern region: cold vasospasm easy to induce inflammatory cells infiltrative thrombosis.