Primary mediastinal large B-cell lymphoma

Primary mediastinal large B-cell lymphoma (PMBCL) is a unique type of B-cell lymphoma probably arising from a putative thymic medullary B cell. It constitutes 6-10 % of all diffuse large B-cell lymphomas (DLBCL), occurring more often in young females. It is characterised by a diffuse proliferation of medium to large B cells associated with sclerosis and a degree of compartmentalisation. CD30 staining is observed in the vast majority of cases (~80 %), although it is weaker and less homogeneous than in cHL and anaplastic large-cell lymphoma. Molecular analysis shows it to be distinct from other types of DLBCL. PMBCL is characterised by an invasive anterior mediastinal mass, often producing local compressive symptoms. Some retrospective analyses suggested that it might respond better to third-generation chemotherapy regimens than to the more commonly used CHOP. However, the addition of rituximab reduced these differences and R-CHOP is now the most widely used treatment, as it is for other types of DLBCL. The role of consolidation with local radiotherapy, which is often used to treat residual mediastinal masses, still remains unclear. Treatment with R-CHOP followed by radiation therapy has excellent results, with a 5-year survival of 70-85 %. The role of FDG-PET scanning is the subject of prospective studies, and it is hoped that in the future, this will allow the de-escalation of radiation therapy based upon more accurate prognostic information as treatment proceeds. © Springer-Verlag Berlin Heidelberg 2014.