Cryoglobulinemias and connective tissue diseases.

Cryoglobulinemias in connective tissue diseases (CTD) represent, according to various authors, 12-30% of all cryoglobulinemia cases. Among CTD, systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and Sjögren's syndrome are the diseases most frequently involved in the presence of cryoglobulins (8-48%). The cryoglobulinemias are mostly of the third type and sometimes of the second type. When clinical symptoms are present, usually they are represented by Raynaud's phenomenon, arthralgias, urticaria, purpura and liver involvement. However, the presence of cryoglobulins in a patient with CTD often does not correlate with clinical picture and other laboratory findings. Eight of our 28 cases (15 SLE and 13 RA) showed third type cryoglobulinemias (7 IgM-IgG and one IgM-IgG-Clq) with a remarkable decrease of serum C4 levels.