Evidence for immunoglobulin-mediated vasculitis caused by monoclonal gammopathy in monoclonal gammopathy of unclear significance prompting oncologic treatment

Although it is unquestionable that monoclonal gammopathy causes occlusive nonvasculitic vasculopathy,1 it is not clear yet, if it can cause immunoglobulin-mediated leukocytoclastic vasculitis (LcV) and how vigorously both conditions should be treated in monoclonal gammopathy of unclear significance (MGUS). In the recent nomenclature of cutaneous vasculitides (addendum to the CHCC2012),2 vasculitis in MGUS is mentioned as a possible, so-far unproven entity. Previous case reports did not sufficiently or explicitly distinguish it from occlusive vasculopathy. Adding to this dilemma is a lack of consensus with oncologists if or when chemotherapies are justified in MGUS with a paraprotein-associated disease. We provide evidence by means of 2 cases of MGUS that monoclonal gammopathy can cause primary immunoglobulin-mediated LcV and that its oncologic treatment abolishes it.