Abstract

Monoclonal Gammopathy of Undetermined Significance (MGUS) is a common entity with prevalence increasing with age. While most cases are asymptomatic, a minority of cases may be associated with end organ damage through mechanisms outside of deposition of the monoclonal immunoglobulin or light chain produced by the culprit clonal cell population. Such cases represent the unique clinical entity of monoclonal gammopathy of “clinical” or “cutaneous” significance (MGCS) and have unique therapeutic implications [1-3]. Treatment strategies include chemotherapy targeting the aberrant clone-producing M protein or systemic immunomodulatory agents [4]. Here we present the case of a 35-year-old male with severe cutaneous leukocytoclastic vasculitis (LCV) secondary to immunoglobulin A (IgA) MGUS with presumptive gastrointestinal vasculitic manifestations that responded to moderate to high dose corticosteroids but failed steroid sparing efforts with dapsone, colchicine, mycophenolate, rituximab and methotrexate. He was treated with cyclophosphamide, bortezomib, and dexamethasone with subsequent normalization of paraprotein production and complete resolution of skin lesions and gastrointestinal symptoms. He remains in remission and off all medical therapy.