FIBRILLAR CRYSTAL-STRUCTURE IN ESSENTIAL MONOCLONAL IGM KAPPA-CRYOGLOBULINEMIA

In monoclonal IgG cryoglobulinemia, two types of crystallization have been demonstrated with electron microscopy at high magnification. In c ontrast, little information is available on well-defined crystallizati on in cases of monoclonal IgM cryoglobulinemia. We present a case of p ure monoclonal IgM kappa cryoglobulinemia and rapidly progressive glom erulonephritis occurring in a 75-year-old woman. We detected unequivoc al formation of fibrillar crystal structure within intraglomerular mac rophages on electron microscopy: the structure accords with that in a case of monoclonal IgG cyroglobulinemia described in the literature.