CD4 and vasculitis: The histopathological features of chronic urticaria are characterized by a perivascular infiltrate around the venules without vasculitis or immune complex deposits at the expense of CD4+ cells with mixed Th1/Th2 characteristics and monocytes, but no B lymphocytes, and a variable presence of granulocytes (polymorphonuclear cells, eosinophils, basophils) that form a late-phase infiltrate.