Hx: 58 y M polysubstance user presented 4 d after last cocaine use with painful pruritic rash/polyarthralgyasLab: high CRP, leukopenia; p-ANCA-; c-ANCA-; ANA-; RA-; HCV/HIV neg Skin biopsy:acute/chronic inflammation of superficial derma, acute perivascular inflammation in deeper derma; acute leukocytoclastic vasculitis; eosinophilic infiltrate Dx: cutaneous levamisole induced vasculitis Tx: steroids. The gene discussed is PRTN3; the disease is hypersensitivity vasculitis.