Primary mediastinal (thymic) large B cell lymphoma

Primary mediastinal (thymic) large B-cell lymphoma is a distinct type of diffuse large B-cell lymphoma involving the mediastinum, recognized in the WHO 2008 classification.[1][2]:370–374

Primary mediastinal (thymic) large B cell lymphoma
Other namesMediastinal large B cell lymphoma, primary mediastinal large B-cell lymphoma (PMLBCL), mediastinal large B-cell lymphoma
SpecialtyHematology, oncology

Signs and symptoms

Superior vena cava syndrome occurs in 30–50%, and pleural or pericardial effusions occur in about one-third.[3]

Pathophysiology

PMLBCL arises from a putative thymic peripheral B cell.[3][4] It has several distinctive biological features.[3] Molecular analysis shows that PMLBCL is distinct from other types of diffuse large B-cell lymphomas (DLBCL).[4] MAL gene expression is seen in 70%, unlike other diffuse large B-cell lymphomas.[2]:370 Gene expression profiling shows considerable variance from other DLBCLs and similarity to Hodgkin disease.[5]:290–293

PMLBCL is CD20 positive, expresses pan-B markers including CD79a, and has clonal immunoglobulin gene rearrangements and mRNA but paradoxically does not express cytoplasmic or cell surface immunoglobulin.[2]:370

Clinically, PMLBCL is unusual in several respects. Despite 80% PMLBCL being stage I or II, the presenting anterior mediastinal mass is often over 10 cm and is locally invasive of lung, chest wall, pleura, and pericardium.[3] At initial presentation, PMLBCL is usually confined to mediastinum, but its bulk, rather than additional adenopathy, can sometimes be palpated at the low neck.[3] Increased LDH is seen in approximately 75%,[2]:370[3] but unlike other large cell lymphomas, no increase in beta-2 microglobulin is seen even when bulky[2]:370 which may relate to defective major histocompatibility complex expression.[2]:370

Treatment

Multiagent chemotherapy is recommended, but the preferred regimen is controversial, as is consolidative radiotherapy.[3][6][7][8]

Epidemiology

It affects primarily young adults; the median age is 37 years.[2]:370 It is more common in females.[3]

Grey zone lymphoma

"In-between CHD and NHL"[3][6][9][10]

See also

References
  1. Swerdlow, Steven H.; International Agency for Research on Cancer; World Health Organization (2008). WHO classification of tumours of haematopoietic and lymphoid tissues. World Health Organization classification of tumours. 2 (4th ed.). International Agency for Research on Cancer. ISBN 9789283224310.
  2. Jaffe, ES; Harris NL; Vardiman JW; Campo E; Arber DA (2011). Hematopathology (1st ed.). Elsevier Saunders. ISBN 9780721600406.
  3. Armitage, JO; Mauch PM; Harris NL; et al. (2010). "Chapter 21". Non-Hodgkin Lymphomas (2nd ed.). Lippincott Williams & Wilkins. ISBN 9780781791168.
  4. Martelli M, Di Rocco A, Russo E, et al. (2015). "Primary mediastinal lymphoma: diagnosis and treatment options". Expert Rev Hematol. 8 (2): 173–86. doi:10.1586/17474086.2015.994604. PMID 25537750.
  5. Sweetenham, J. Lymphomas (Emerging Cancer Therapeutics V3 I2). Demos. November 2, 2012. ISBN 9781936287789
  6. http://www.nccn.org/professionals/physician_gls/pdf/nhl.pdf
  7. Faris JE, LaCasce AS (2009). "Primary mediastinal large B-cell lymphoma". Clin Adv Hematol Oncol. 7 (2): 125–33. PMID 19367254.
  8. Dabrowska-Iwanicka A, Walewski JA (2014). "Primary mediastinal large B-cell lymphoma". Curr Hematol Malig Rep. 9 (3): 273–83. doi:10.1007/s11899-014-0219-0. PMC 4180024. PMID 24952250.
  9. Hutchinson CB, Wang E (2011). "Primary mediastinal (thymic) large B-cell lymphoma: a short review with brief discussion of mediastinal gray zone lymphoma". Arch. Pathol. Lab. Med. 135 (3): 394–8. doi:10.1043/2009-0463-RSR.1. PMID 21366467.
  10. Grant C, Dunleavy K, Eberle FC, et al. (2011). "Primary mediastinal large B-cell lymphoma, classic Hodgkin lymphoma presenting in the mediastinum, and mediastinal gray zone lymphoma: what is the oncologist to do?". Curr Hematol Malig Rep. 6 (3): 157–63. doi:10.1007/s11899-011-0090-1. PMC 6324553. PMID 21590365.
Classification
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