MyPathologyReport
April 3, 2023
What is CD20?
CD20 is a protein primarily expressed on the surface of B cells, a type of white blood cell that plays a key role in the immune system’s defense against infections. CD20 is expressed throughout the entire B cell development process, from pre-B cells to mature B cells, but is not present on plasma cells, which are the cells that make antibodies. Other B cell markers include CD19, CD79, and PAX-5.
What does CD20 do?
CD20 is involved in the regulation of B cell activation, differentiation, and proliferation.
What tests are used to look for CD20?
Two common tests used to look for CD20 in a tissue sample are immunohistochemistry and flow cytometry. Immunohistochemistry is performed on a tissue sample attached to a glass slide. The slide is then examined under the microscope. Flow cytometry uses a special machine to count and analyze the number of cells in a tissue sample that are making CD20.
What does positive for CD20 mean?
Positive for CD20 means that the cells in the tissue sample were producing CD20. Both normal and cancerous B cells are typically positive for CD20.
What does negative for CD20 mean?
Negative for CD20 means that the cells in the tissue sample were not producing CD20. Other than B cells, most types of cells will be negative for CD20.
Can normal cells be positive for CD20?
Yes. Normal, healthy B cells are positive for CD20. These cells are found throughout the body.
What types of cancers are positive for CD20?
Most lymphomas that start from B cells will be positive for CD20.
CD20-positive lymphomas include:
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