Here immune complexes, consisting of monoclonal IgM with rheumatoid factor activity and polyclonal IgG (type II MC), or polyclonal oligoclonal IgM and IgG (type III MC), precipitate and cause small vessels’ obstruction and ischemia, leading to leukocytoclastic vasculitis [2]. The gene discussed is CD40LG; the disease is hypersensitivity vasculitis.