Cryoglobulinemia and cryoglobulinemic vasculitis: etiological aspects and pathophysiological associations

The term cryoglobulinemia (CG) is used when detecting serum immunoglobulins that reversibly precipitate and form a gel at a temperature below 37 °C and dissolve when the temperature rises above 37 °C. Type I CG consists of only one isotype or a subclass of monoclonal immunoglobulins, while types II and III are classified as mixed CG (MCG) that is primarily characterized by the presence of immunoglobulins G and M. Types II and II-III MCG can result in cryoglobulinemic vasculitis (CGV) more frequently, whereas type III can lead to this condition less frequently. The presence of type I cryoglobulins is always associated with B-cell lymphoproliferative diseases. On the contrary, type II or type III MCG is more commonly associated with systemic autoimmune diseases and chronic infections. Thus, hepatitis C virus infection contributes to the development of MCG in 80–90% of cases. CGV is considered a rare disease worldwide (