immune complexes and complement can cause a clinical syndrome of cutaneous small-vessel vasculitis characterized by systemic vasculitis and inflammation termed cryoglobulinemic vasculitis. Accordingly, type II and type III cryoglobulinemic diseases are often grouped together and referred to as mixed cryoglobulinemia or mixed cryoglobulinemic disease. The monoclonal IgM involved in Type I cryoglobulinemic diseases lacks rheumatoid factor activity. More recent high resolution protein electrophoresis methods have detected a small monoclonal immunoglobulin component in type III cryoglobulins and/or a micro-heterogeneous composition of oligo-clonal (i.e., more than one monoclonal) immunoglobulin components or immunoglobulins with structures that do not fit into any classifications in the cryoglobulins of ≈10% of type II and III disease cases. It has been proposed that these cases be termed an intermediate type II-III variant of cryoglobulinemic disease and that some of the type III cases associated with the expression of low levels of a one or more isotypes of circulating monoclonal immunoglobulin(s) are in transition to type II disease. Signs and symptoms The clinical features of cryoglobulinemic disease can reflect those due not only to the circulation of cryoglobulins but also to any underlying hematological premalignant or malignant disorder, infectious disease, or autoimmune syndrome. The following sections of clinical features focuses on those attributed to the cryoglobulins. Cryoglobulins cause tissue damage by three mechanisms; they can: a) increase blood viscosity thereby reducing blood flow to tissues to cause the hyperviscosity syndrome (i.e., headache, confusion, blurry or loss of vision, hearing loss, and epistaxis; b) deposit in small arteries and capillaries thereby plugging these blood vessels and causing infarction and necrosis of tissues including in particular skin (e.g., ears), distal extremities, and kidneys; c) in type II and type III disease, deposit on the endothelium of blood vessels and activate the blood complement system to form pro-inflammatory elements such as C5a thereby initiating the systemic vascular inflammatory reaction termed cryoglobulinemic vasculitis. Essential cryoglobulinemic disease The signs and symptoms in the increasingly rare cases of cryoglobulinemic disease that cannot be attributed to an underlying disease generally resemble those of patients suffering Type II and III (i.e., mixed) cryoglobulinemic disease. Type I cryoglobulinemic disease Signs and symptoms due to the cryoglobulins of type I disease reflect the hyperviscosity and deposition of cryoglobulins within the blood vessels which reduce or stop blood perfusion to tissues. These events occur particularly in cases where blood cryoglobulin levels of monoclonal IgM are high in patients with