Unusual manifestations of monoclonal gammopathies. Autoimmune and idiopathic syndromes

Manifestations of monoclonal gammopathies are due to four broad mechanisms: destruction of bones, bone marrow, and normal tissues by an expanding tumor; nonspecific effects of large amounts of circulating paraproteins leading to hyperviscosity; autoantibody specificity of paraproteins that give rise to cryoglobulinemia, cold agglutinin disease, and other autoimmune phenomena, as well as incidental binding to bacterial antigens and haptens; and idiopathic syndromes due to as yet unidentified tumor products or other mechanisms. A review with an emphasis on the autoimmune and idiopathic manifestations of monoclonal gammopathies is presented.