Bone marrow smear from a patient with lymphoplasmacytic lymphoma and an IgM spike (Waldenstrom macroglobulinemia). There is an intranuclear inclusion in a lymphocyte (arrow) that represents precipitated IgM.
From Brunning, RD, McKenna, RW. Tumors of the bone marrow. Atlas of tumor pathology (electronic fascicle), Third series, fascicle 9, 1994, Washington, DC. Armed Forces Institute of Pathology.