Initial bone marrow findings in multiple myeloma. Significance of plasma cell nodules.

A retrospective review of bone marrow specimens from 235 patients with multiple myeloma and 148 patients with reactive plasmacytosis was performed in an attempt to evaluate the usefulness of bone marrow sections in distinguishing between these conditions. Although the presence of large homogeneous nodules and/or infiltrates of plasma cells in bone marrow sections remains the best criterion for the diagnosis of myeloma, a few specimens (2%) from patients with reactive plasmacytosis also showed this feature. In addition, 26% of the patients with myeloma had bone marrow sections that were considered nondiagnostic in that they lacked recognizable homogeneous nodules and/or infiltrates of plasma cells. Finally, distinguishing multiple myeloma from bone marrow involvement by lymphoplasmacytic lymphomas can be very difficult, if not impossible, based on findings in the sections alone.