Lymphoproliferations in the bone marrow: identification and evolution, classification and staging.
Bone marrow biopsies from 3229 patients with lymphoproliferative disorders and 1156 patients with benign or reactive lymphoproliferations were investigated and criteria for distinguishing between them are given. Bone marrow involvement was found in 89% of multiple myeloma, 64% of non-Hodgkin's lymphomas and 8% of Hodgkin's disease. According to the predominant proliferative cell type there were five major entities in multiple myeloma and non-Hodgkin's lymphomas: (1) plasmacytic; (2) lymphocytic; (3) hairy cell; (4) immunocytic; (5) centrocytic. These were further classified into distinct subtypes each of which had independent prognostic significance. The mode of spread of the lymphoproliferative disorders in the bone marrow showed one of six architectural patterns, which together with the quantity of infiltration in the biopsy (reflecting the tumour cell burden) had significant predictive value. These results demonstrate the value of bone marrow biopsies in the identification, classification and staging of lymphoproliferative disorders, as well as in monitoring the course of disease and the response to therapy.