'Silk route disease' (Behçet's disease).

Behçet's disease is a multisystem disorder in which orogenital ulceration is associated with troublesome generalized uveitis, erythema nodosum, pyoderma, dermatographism, seronegative arthritis, and neurologic and cardiovascular symptoms. There is no diagnostic laboratory test; the diagnosis is based on the disorder's multisystem clinical features. A points scoring system is helpful in distinguishing it from other multisystem disorders that mimic it. It occurs most frequently in an area coinciding with the old Silk Route, between latitudes 30 degrees and 45 degrees north, in Asian and Eurasian populations, and it has an HLA-B51 affinity. The cause remains unknown, but a postulated trigger factor is a herpesvirus with cofactors that include ethnic group, human leukocyte antigen affinities, T-cell and autonomic imbalance, circulating immune complexes, autoimmunity, blood viscosity, decreased fibrinolysis, and zinc deficiency. Treatment includes administering corticosteroids, azathioprine, chlorambucil, cyclosporine, and colchicine, and fibrinolytic therapy.