Bone Marow (BM) Involvement in Diffuse Large B Cell Lymphoma (DLBCL): Clinical Impact of Discordant Disease.

Abstract

Background and Methods: Most published studies have suggested that survival of de novo DLBCL with discordant BM involvement by small B cell lymphoma is indistinguishable from patients having a negative staging BM. The aim of the study was to investigate the incidence and clinical impact of BM involvement by concordant and discordant B cell lymphoma in patients with DLBCL seen in a single institution over a 5 year period (1\\1\\2000 – 31\\12\\2004). The cases were identified from pathology records and BCCA Lymphoid Cancer Database.Results: The group of interest for this study comprised 652 patients with de novo DLBCL with staging marrow available for review. 60 of 652 (9.2%) of patients with DLBCL had concordant large B-cell lymphoma in their bone marrow. 523 (80.2%) were negative, 16 patients showed what we considered to be atypical lymphoid (ALH) infiltrates lacking definitive features of malignancy. In 50 patients (7.7%) the bone marrow showed discordant histology with predominantly small B-cells, some showing paratrabecular localization. In total there were five cases of TCRBCL in the study, three with marrow involvement. Furthermore, all 54 cases of primary mediastinal B-cell lymphoma (PMBCL) had a negative BM. Of the 652 cases with DLBCL with staging bone marrows available, merging the pathology and clinical databases resulted in 599 patients with complete clinical records. Of these, bone marrows were either not done or deemed inadequate in 101 cases. Therefore, there were 488 patients with DLBCL with an interpretable marrow of which 344 had advanced stage disease. Staging marrows in these patients were negative = 264, positive 41, discordant 28, and ALH 11. The overall survival and progression free survival were strongly affected by the IPI score for these 344 cases (P<0.00001) (see figure). Compared to those without BM involvement patients with concordant large B-cell lymphoma in their BM (n=41) had the worst outcome and those with discordant small B-cell lymphoma in the bone marrow (n=28) had an inferior but intermediate outcome (median survivals (months) = not reached;12 and 20, respectively).Conclusion: Diffuse large B-cell lymphoma is a heterogenous group of lymphomas as demonstrated by gene expression profiling. Our data suggests that discordant low grade B-cell lymphoma in patients who have coincident DLBCL has a poorer prognosis and the presence or absence of BM disease has clinical significance. Though we had very few cases, TCRBCL show a higher incidence of BM involvement in keeping with the reported literature. The absence of marrow disease in PMBCL is consistent with recent data indicating it is a biologically distinct form of DLBCL. [Display omitted]