The unexpected evolution of a case of diffuse large B-cell non-Hodgkin lymphoma

The diffuse large B-cell lymphoma (DLBCL) represents the most common type of aggressive non-Hodgkin's lymphoma with a heterogeneous morphology, biology and clinical presentation. Gene expression profiling studies identified three distinct molecular subtypes of DLCBL arisen from B-cells at different stages of differentiation: germinal center B-cell-like (GCB) DLBCL, activated B-cell-like (ABC) DLBCL, primary mediastinal B-cell lymphoma (PMBL). The most relevant oncogenic pathways in diffuse large B-cell lymphoma are: deregulated B-cell receptor/proliferation signaling, BCL6 and NF-kB constitutive expression, defects in apoptosis and neoangiogenesis. The treatment of DLBCL has been completely modified in the last ten years by combination of anti-CD20 monoclonal antibody (rituximab) and CHOP chemotherapy, which is now the first line therapy. In the last years, there have been reported several cases of progressive multifocal leukoencephalopathy (PML) at patients with rheumatoid arthritis treated with rituximab. Progressive multifocal leukoencephalopathy is possible as an adverse reaction to rituximab at patients treated with R-CHOP for diffuse large B-cell lymphoma.