Discordant bone marrow involvement in diffuse large-cell lymphoma: a distinct clinical-pathologic entity associated with a continuous risk of relapse. From 1975 to 1988, 50 patients with lymph node biopsy-documented diffuse large-cell lymphoma (DLCL) presented with bone marrow involvement. Twenty-four patients (48%) had large-cell lymphoma (LCL) in the bone marrow and were compared with 19 (38%) patients who had small cleaved-cell lymphoma (SCCL) in the marrow. Additionally, seven patients (14%) had mixed small- and large-cell lymphoma (ML) in the marrow. Patients who had LCL marrow involvement were younger (P less than .02) and more frequently had elevated lactic dehydrogenase (LDH) levels (P less than .001), high tumor burden (P less than .01), and more sites of extranodal disease (P less than .05) than those with SCCL in the marrow. The complete response (CR) rate to multiagent chemotherapy was 16.7% in the LCL group and 89.4% in the SCCL group (P less than .001). One third of the patients with LCL in the marrow developed CNS involvement, compared with only one patient in the SCCL group (P = .06). Overall 5-year survival was 79% in patients with SCCL marrow involvement, compared with only 12% in patients with LCL in the marrow (P = .002). Despite a high CR rate, patients with marrow involved by SCCL were at a high continuous risk of relapse with only a 30% failure-free survival at 5 years. We conclude that bone marrow involvement with LCL predicts for extremely poor prognosis with low response rate and short survival. Patients with SCCL in the bone marrow have a high rate of CR and a high rate of 5-year survival; however, there is a high risk of late relapse, and only 15% are in a continuous remission at 8 years. 