Cause:Any vasculitis (Nejm 1997;337:1512) including: giant cell, Takayasu's, polyarteritis, Wegener's, paraneoplastic, inflammatory bowel disease, and immune complex types (anaphylactoid Henoch-Schönlein purpura, cryoglobininemia, SLE, RA, Sjögren's, Goodpastures, Behcet's, scleroderma, and drug- or viral-induced, a continuum from urticaria to erythema multiforme (Urticaria/Erythema Multiforme)