Mediastinum
Hematological neoplasms / lesions
Diffuse large B cell lymphoma

Author: Hanni Gulwani, M.D. (see Authors page)

Revised: 20 June 2018, last major update December 2012

Copyright: (c) 2003-2018, PathologyOutlines.com, Inc.

PubMed Search: Diffuse large B cell lymphoma mediastinum

Cite this page: Gulwani, H. Diffuse large B cell lymphoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/mediastinumdiffuselargeB.html. Accessed July 17th, 2018.
Definition / general
  • Most common primary malignancy of mediastinum, except for Hodgkin lymphoma
  • Symptoms are usually related to local invasion or compression and include dyspnea, cough, chest pain and dysphagia
  • Hoarseness is frequently present due to laryngeal or phrenic nerve palsy
  • Aggressive, 5 year survival of 60%
Epidemiology
  • Often young women (65%) in 20s and 30s or men (35%) in 40s and 50s
Sites
  • Usually anterior mediastinum
  • Usually confined to chest at diagnosis, often presents with superior vena cava syndrome
  • < 25% have extrathoracic involvement after staging
  • May spread to adrenal, bowel, brain, kidney, liver, ovary
  • Bone marrow involvement is extremely rare even in cases of recurrence
Pathophysiology
Clinical features
Prognostic factors
  • Poor prognostic factors: high stage, size > 10 cm, extrathoracic involvement at diagnosis, poor response to chemotherapy, pericardial or pleural effusion at diagnosis
Case reports
  • Mediastinal large B cell lymphoma with rosette formation mimicking thymoma and thymic carcinoid (Histopathology 2006;49:93)
Treatment
  • Responds to chemotherapy
Gross description
  • Bulky anterior intrathoracic mass, often centered in thymus
  • Fleshy, multilobated, poorly delineated, unencapsulated with hemorrhage and necrosis
  • May directly extend to thoracic structures
Microscopic (histologic) description
  • Sheets or irregular clusters of large cells with vesicular or hyperchromatic nuclei with irregular contours / nuclear blebs, prominent nucleoli
  • May appear immunoblastic or resemble Reed-Sternberg cells
  • Amphophilic or clear cytoplasm
  • May trap benign thymocytes
  • May have mixture of small mature lymphocytes in tight perivascular cuffs
  • Usually frequent mitotic figures, apoptosis but no broad zones of necrosis
  • Usually stromal sclerosis
  • Residual thymus may be cystic
Microscopic (histologic) images

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Pleomorphic lymphoid cells

High power view

Figure b

Figures a - d

Primary mediastinal (thymic) large B cell lymphoma

Negative stains
Electron microscopy description
  • No intercellular junctional complexes, pericellular basal lamina, complex nucleoli, premelanosomes, tonofibrils or branching surface microvilli, although filiform projections of cellular membranes may resemble microvilli
Molecular / cytogenetics description
  • IgH and IgL rearrangements, 9p amplification involving REL gene (% unknown)
  • No BCL6 gene rearrangement or mutations