Primary mediastinal large B-cell lymphoma

Primary mediastinal large B-cell lymphoma (PMLBCL) is a unique type of B-cell lymphoma probably arising from a putative thymic medulla B-cell. It constitutes 6-10% of all diffuse large B-cell lymphomas (DLBCL), occurring more often in young females. PMLBCL is characterized by a diffuse proliferation of medium to large B-cells associated with sclerosis and a degree of compartmentalisation. Its main molecular characteristics include: gains in 9p segments, p53 mutations, BCL-2 and MAL gene over-expression, somatic mutations of IgVH genes, BCL-6, PIM-1, PAX-5, RhoH/TTF, and c-MYC, and constitutional NF-κB activation. The gene expression signature of PMLBCL seems to be much closer to classic Hodgkin lymphoma than to DLBCL. PMLBCL is characterized by a locally invasive anterior mediastinal mass, often producing cough, chest pain, dyspnea, and superior vena cava syndrome. Most PMLBCL patients have stage I-II, bulky disease, with pleural or pericardial effusions in a third of cases. Systemic symptoms, mainly fever or weight loss, are present in