Bone marrow histology in monoclonal macroglobulinemia

Histologic sections and smears of aspirated bone marrow particles in 26 cases of monoclonal macroglobulinemia were studied. The bone marrows did not show uniform histologic features. Twenty two patients had various degrees of lymphoid infiltration of the marrow, including nodules of malignant lymphoma, diffuse lymphocytic infiltration, nodular lymphoid hyperplasia, and normal lymphoid nodules. Four patients had no demonstrable lymphoid collections in the marrow. Additional histologic features of the marrows are summarized. A variant of a Dutcher body consisting of multiple PAS positive inclusions that by light microscopy appear intranuclear is described. Even though the average macroglobulin levels were higher in patients with abnormal lymphoid infiltrates than in patients with normal or no lymphoid collections, there were considerable overlap between individual patients' values in the different groups. Similarly, no correlation between macroglobulin levels and other histologic features could be established. Patients with monoclonal macroglobulinemia represent a spectrum including benign monoclonal gammopathy, lymphoproliferative disorders of the marrow, nodal or extranodal lymphomas. The separation of Waldenstrom's macroglobulinemia by arbitrary criteria does not appear justified.