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Lymphoma - B cell neoplasms

Non-Hodgkin lymphoma - general


Reviewer: Nikhil Sangle, M.D., University of Utah and ARUP Laboratories (see Reviewers page)
Revised: 6 February 2012, last major update February 2011
Copyright: (c) 2001-2012, PathologyOutlines.com, Inc.

General
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● Clonal lymphoproliferative disorder
● Heterogenous neoplasms; diagnosis of Non-Hodgkin lymphoma (NHL) gives far less information than type of NHL

Epidemiology
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● Increasing incidence over past 40 years for unknown reasons
● 50,000 new cases in US per year, many HIV related

Etiology
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● Putative cell of origin is known for most B cell NHLs but not most T cell NHLs
● Often associated with a cytogenetic translocation that puts a proto-oncogene or apoptotic gene next to a gene that is constitutively active in lymphocytes

Clinical features
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● 80% are B cell, NK are rare
● All are monoclonal as determined by light chain restriction or antigen receptor gene rearrangement (immunoglobulin or T cell receptor)
● Characteristic patterns of tissue involvement occur, such as follicular lymphomas in B cell areas, T cell lymphomas in paracortical zones
● Most tumors are widely disseminated at diagnosis, requiring systemic therapy for cure; thus, staging is not as important as in Hodgkin lymphoma
● In adults, most common subtypes are follicular lymphoma, diffuse large B cell lymphoma, CLL/SLL, multiple myeloma
● In children, most common subtypes are Burkitt or Burkitt-like, lymphoblastic leukemia/lymphoma, large B-cell lymphoma and anaplastic large cell lymphoma; in children, follicular and marginal zone lymphoma are uncommon; tumors are usually extranodal, aggressive, often leukemic; but better survival than adults
● Risk factors include immunodeficiency (primary or secondary), autoimmune disorders (Sjogren, rheumatoid arthritis, Hashimoto thyroiditis), viruses (HIV, ATLV, KSHV/HHV8, HTLV-1), Helicobacter pylori infection, radiation, chemotherapy
● More likely than Hodgkin lymphoma to: be extranodal, disseminated, involve peripheral blood, bone marrow, GI, skin or CNS
● Less likely than Hodgkin lymphoma to: have B symptoms (only 20% versus 40% in Hodgkin lymphoma) or have mediastinal involvement (except that mediastinal involvement is common in lymphoblastic and mediastinal large B cell lymphoma)
● Poor prognostic factors, based on International Prognostic Index (IPI): age at diagnosis > 60 years, presence of B symptoms, ECOG/Zubrod performance status 2-4 vs. 0-1, elevated serum LDH, more than 1 nodal or extranodal site of disease, advanced vs. localized disease

Treatment
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● See particular tumors; addition of rituximab (anti-CD20 antibody) to most B-cell NHL treatment regimens has led to improved survival

Cytology
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● Sensitivity and specificity of diagnosis with fine needle aspiration increases with use of flow cytometry
● Cytology is a good diagnostic tool in most lymphomas except marginal zone lymphoma and Hodgkin lymphoma (Arch Pathol Lab Med 2000;124:1792)

Negative stains
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● Usually HER2 (Arch Pathol Lab Med 2002;126:574)

Differential diagnosis
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● Florid immunoblastic proliferations of infectious mononucleosis or other viral infections, particularly in children, resemble lymphoma
● Autoimmune lymphoproliferative syndrome patients with Fas or FasL deficiency may develop giant lymphadenopathy resembling EBV+ post-transplant lymphoproliferative disease (Am J Surg Pathol 1999;23:829)

End of Lymphoma - B cell neoplasms > Non-Hodgkin lymphoma - general


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