Primary Mediastinal B-Cell Lymphoma: A Review of Pathology and Management

Abstract

PMBL has unique clinical and biologic characteristics that are radically different from those of other types of diffuse large B-cell lymphoma. Although relatively rare, its aggressive growth and its occurrence in young patients increase the clinical relevance of this entity. The consistent recognition and study of PMBL will allow the development of new approaches to its management.

Primary mediastinal B‐cell lymphoma

“…PMBL normally presents with a bulky tumor in the anterior mediastinum that is rapidly progressive and may give rise to local compressive effects including dyspnea, cough, dysphagia and superior vena caval obstruction 4 ( Figure 1). The disease affects females more frequently than men, and peaks in incidence in the third or fourth decades.…”

Aberrant somatic hypermutation in primary mediastinal large B-cell lymphoma

“…Also, PMLBCL rarely has extrathoracic disease at diagnosis, and at relapse preferentially involves extranodal sites. 2 Pathologically, PMLBCL is typically associated with various degrees of sclerosis and consists of a diffuse proliferation of large cells expressing B-lineage markers but lacking surface immunoglobulins. 1,2 At the molecular level, PMLBCL exhibits several genetic abnormalities, including gains of 9p and X that are otherwise absent in DLBCL, and lack genetic lesions, such as BCL-2 and BCL-6 rearrangements that are typically associated with DLBCL.…”

“…2 Pathologically, PMLBCL is typically associated with various degrees of sclerosis and consists of a diffuse proliferation of large cells expressing B-lineage markers but lacking surface immunoglobulins. 1,2 At the molecular level, PMLBCL exhibits several genetic abnormalities, including gains of 9p and X that are otherwise absent in DLBCL, and lack genetic lesions, such as BCL-2 and BCL-6 rearrangements that are typically associated with DLBCL. 2 An aberrant activity of the somatic hypermutation (SHM) mechanism, targeting the 5 0 sequences of PIM-1, PAX-5, RhoH/ TTF and c-MYC proto-oncogenes, has been advocated as a molecular feature distinctive of DLBCL.…”

Primary mediastinal B‐cell lymphoma with sclerosis: Report of 11 cases treated with intensified‐CHOP plus radiotherapy

“…Its peculiar morphologic and molecular genetic profile, as well as the aggressive clinical evolution, has been widely described [2,3].…”

“…It usually arises in young females with a unique bulky mediastinal lesion and possible pleural or pericardial involvement, superior vena cava obstruction, and high serum lactate dehydrogenase levels (LDH) [2,3].…”