Cover figure shows the following: (Top left) Retinal hemorrhages and venous dilation from hyperviscosity. (Top center) Bone marrow aspirate showing lymphocytes and plasma cells consistent with Waldenström's macroglobinemia. (Top right) Immunofluorescence with IgM antisera. (Bottom left) Densitometer tracing and cellulose acetate electrophoretogram showing a polyclonal gammopathy. (Bottom center) Densitometer tracing and cellulose acetate electrophoretogram showing a monoclonal gammopathy. (Bottom right) Immunofixation showing an IgM monoclonal protein. Cover figure courtesy of Robert A. Kyle, MD, and Philip R. Greipp, MD (Mayo Clinic, Rochester, MN).È