Diffuse large-cell lymphoma with monoclonal IgM kappa and cold agglutinin.

A patient with diffuse large-cell lymphoma associated with a serum monoclonal IgM kappa and a cold agglutinin is described. The cold agglutinin was the initial manifestation of disease and was apparent for at least two months before the diagnosis of lymphoma. The lymphoma cells had surface and cytoplasmic IgM kappa.