Diffuse large B-cell lymphoma (DLBCL) involving the bone marrow in a 60 y/o female. The tumor cells were CD20 positive. Image copyright: Pathorama.ch. Bone marrow involvement is seen in about 15% of DLBCL cases. The tumor morphology in the bone marrow may be concordant (for e.g. DLBCL in both bone marrow as well as primary nodal site) or discordant (e.g. follicular lymphoma in bone marrow and DLBCL in primary nodal site). Discordant bone marrow morphology has much better prognosis and survival (almost the same as no bone marrow involvement) as compared to the cases with concordant morphology. Image copyright: pathorama.ch.