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	Non-Hodgkin's Lymphoma
	- Introduction - Causes - Clinical Picture - Diagnosis - Pathology - Staging - Treatment

A diagnosis of NHL, as well as suspected relapses, should be made based on the pathologic examination of a lymph node whenever possible.

Fine-needle Aspiration (FNA)

FNA is accepted as the primary tool in the diagnosis of NHL. FNA provides faster turnaround, less morbidity and mortality, and decreased cost compared with surgical biopsy.

Nevertheless, it should be confirmed with an excisional biopsy in initial diagnosis due to the fact that it is unable to evaluate the histological architecture and the degree of necrosis.

The documentation of recurrent lymphoma is a widely accepted use of FNA.

• The accuracy of fine-needle aspiration (FNA) is variable. The sensitivity of FNA diagnosis in NHL ranges from 66% to 100%.
• Using a combination of cytomorphologic (CM) examination and FC analysis confers a substantial improvement in specificity.

Excisional biopsy

Excisional biopsy is the gold-standard by which NHL is diagnosed.

• Sensitivity depends mainly on the adequacy of the material provided to the pathologist and ranges from 98% to 100%.

• Specificity of excisional biopsy in the hands of a capable pathologist is 100%. Conventional histologic analysis of the bone marrow can detect 1 lymphoma cell infiltrating 20 normal cells.

Immunological studies

Monoclonal antibodies directed against cell surface antigens expressed on lymphoid cells and molecular techniques to define immunoglobulin and T cell receptor gene rearrangements are sensitive tools with which to assess tumor cell infiltration. Immunophenotypic studies can help to determine histologic subtypes of lymphomas in cases where conventional histology is ambiguous, which may have an impact on treatment.

• Immunologic flow cytometric and Southern blot analysis each improve this level of detection to approximately 1 lymphoma cell in approximately 100 normal cells.

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Immunophenotyping (IPT)

Immunophenotyping refers to the technique of identifying molecules that are associated with lymphoma cells and that help to characterize them. The molecules are identifiable because, in almost all analyzable cases, they are expressed on the outer cell surface membrane. The molecules are identified by using special antibodies that bind to them specifically. Each of these identifying molecules are given a cluster designation, or CD number, meaning that a known cluster of antibodies were binding to this known antigen. These are useful in confirming the diagnosis of lymphoma in suspicious cases and in determining the various subtypes of lymphoma.

The basic immunophenotypic patterns are:

1. Almost all lymphoid cells are reactive for CD45 (leukocyte common antigen, or LCA).

2. B-lymphocytes

• Almost all B-cells are reactive for CD19, CD20 and CD22.
• Certain low-grade B-cell lymphomas are reactive for two markers otherwise usually found on T-cells: CD5 and CD43.

• Follicular center cell lymphomas (as well as lymphoblastic lymphomas) are frequently CD10(+).

3. T-lymphocytes

• Pan T-cell markers (present on almost all T-cells) include CD2, CD3, CD5, and CD7.

• Most T-cells mark with either CD4 (helper cells) or CD8 (suppressor cells or cytotoxic cells).

Immunophenotype of lymphoma subtypes

• Diffuse large B-cell CD20+, CD3-, CD5-, CD45+

• Mediastinal large B-cell CD20+, CD3-, CD45+
   

• Follicular CD20+, CD3-, CD10+, CD5-

• Burkitt CD20+, CD3-, CD10+, CD5-, Tdt-
   

• Small lymphocytic CD 20+, CD3-, CD10-, CD5+, CD23+

• Mantle cell CD20+, CD3-, CD10-, CD5+, CD23-, CD 43+, PRAD1+
   

• MALT CD20+, CD3-, CD 10-, CD5-, CD23-

• Marginal zone CD20+, CD3-, CD 10-, CD5-, CD23-
   

• Lymphoblastic CD20-, CD3+, Tdt+

• Peripheral T-cell CD20-, CD3+

• Anaplastic large cell CD20-, CD3+, CD30+, CD15-, EMA+, ALK+

• Hodgkin CD30+, CD15+

Cytogenetic and molecular studies

Biologic studies, including cytogenetics, and molecular techniques, are being integrated into diagnosis, staging, and minimal disease detection. Cytogenetic studies can help to determine histologic subtypes of lymphomas in cases where conventional histology is ambiguous, which may have an impact on treatment.

• Cytometric and Southern blot analysis, similar to IPT, each improve this level of detection to approximately 1 lymphoma cell in approximately 100 normal cells.

For those NHLs with known chromosomal translocations, it is possible to identify unique chromosomal breakpoints. For example, detection of the t(14;18) of follicular lymphomas or in MCL t(11;18) can be undertaken by employing the technique of polymerase chain reaction (PCR).

• PCR techniques can detect 1 tumor cell in 105 to 106 cells. Whether the detection of this translocation is indicative of relapse in those who have achieved CR is controversial.

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