Immunophenotyping, Cytogenetic, and Mutational Analysis

Immunophenotyping

Immunophenotyping refers to tests used to identify unique cell types based on the types of antigens or markers on the cell’s surface.1 Such tests are employed at the initial diagnostic workup and is essential to establish a diagnosis of MZL.1

Immunophenotype, in addition to histology and cytogenetic studies, helps establish the diagnosis of MZL.1 The immunophenotype characteristic of MZL is shown in the table below.

Subtype Typical immunophenotype1
Marginal Zone Lymphoma (MZL) CD10-, CD5-, CD20+, CD23-/+, CD43-/+, and cyclin D1-; BCL2- follicles

Two common immunophenotyping tests are immunohistochemistry (IHC) and flow cytometry (FC).1

Immunohistochemistry (IHC)2

  • A lab test that uses labeled antibodies to test for certain antigens (markers) in a tumor sample
  • Antibodies are usually linked to an enzyme or a fluorescent dye
  • When the antibodies bind to the antigen in the tissue sample, the enzyme or dye is activated, and the antigen can be seen under a microscope

Flow Cytometry (FC)2

  • A method of characterizing the antigens in a tumor sample by staining them with a light-sensitive dye, placing them in a fluid, and passing them in a stream before a laser or other type of light
  • The measurements are based on how the light-sensitive dye reacts to the light
  • FC also measures the number of cells in a sample, the percentage of live cells in a sample, and certain characteristics of cells, such as size, shape, and the presence of tumor markers on the cell surface

Cytogenetics

Cytogenetic tests, which combine principles of cytology (the study of cells using a microscope) and genetics, are used in certain circumstances for the diagnosis of MZL. More specifically, genetic abnormalities detected by karyotyping or fluorescent in-situ hybridization (FISH), have become increasingly important in defining specific NHL subtypes.1,2

  • Karyotyping: a method by which chromosomes are visualized, allowing detection of large rearrangements or abnormalities3,4
  • FISH: a method that detects the presence of specific proteins in a biologic sample using fluorescently-tagged antibodies that bind to antigens of interest5

In MZL, translocations between 2 chromosomes, including t(11;18) and t(1;14), or chromosomal deletions, including, del(13q), del(7q), that can be detected by FISH and/or karyotyping may be useful in select cases.1

Molecular Profiling

Molecular analysis may be useful during diagnosis of MZL in select cases.1

If molecular profiling tests are ordered, DNA is isolated from a patient and its entire sequence is determined or a panel of known cancer-related genes are sequenced.6,7 Such profiling will detect changes in specific genes in the tumor cells unique to the disease, which may inform diagnosis, prognosis, and treatment.6

Additional molecular tests may be useful in specific cases1:

  • Molecular analysis to detect antigen receptor gene rearrangements
  • MYD88 mutation status to differentiate MZL from another subtype of NHL called Waldenstrom macroglobulinemia
  • PCR to detect t(11;18), a translocation between chromosomes 11 and 18
  • BRAF testing to differentiate cases of splenic MZL from another subtype of NHL called hairy cell lymphoma

References: 1. Referenced with permission from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for B-Cell Lymphomas V.4.2019. © National Comprehensive Cancer Network, Inc. 2019. All rights reserved. Accessed July 10, 2019. To view the most recent and complete version of the guideline, go online to NCCN.org. NCCN makes no warranties of any kind whatsoever regarding their content, use or application and disclaims any responsibility for their application or use in any way. 2. National Cancer Institute. NCI Dictionary of Cancer Terms. https://www.cancer.gov/publications/dictionaries/cancer-terms. Accessed June 12, 2019. 3. Gulley ML et al. Genetic Tests To Evaluate Prognosis and Predict Therapeutic Response in Acute Myeloid Leukemia. J Mol Diagn. 2010;12(1):3-16. 4. O'Connor, C. Karyotyping for chromosomal abnormalities. Nature Education. 2008;1(1):27. 5. Bishop R. Applications of fluorescence in situ hybridization (FISH) in detecting genetic aberrations of medical significance. Bioscience Horizons. 2010;3(1):85-95. 6. Johansen Taber KA, Dickinson BD, Wilson M. The promise and challenges of next-generation genome sequencing for clinical care. JAMA Intern Med. 2014;174(2):275-280. 7. Rosenquist R et al. Clinical impact of recurrently mutated genes on lymphoma diagnostics: state-of-the-art and beyond. Haematologica. 2016;101(9):1002-1009.