Approach to the diagnosis of discordant lymphoma. In the staging of DLBCL, a BM biopsy should be performed if there is increased PET-FDG uptake or for other clinical reasons such as the presence of cytopenias. If discordant indolent lymphoma is diagnosed in the BM, clonality studies should be considered if available. In contrast to concordant BMI in DLBCL, studies suggest that discordant involvement (with indolent disease in the BM) is not associated with an increased risk of CNS disease.