Test Name: CD20
CD20 is expressed on the membrane of mature B-cells and precursor B-cells at some stages of maturation. It is also expressed at variable intensity in most mature B-cell non-Hodgkin lymphomas, many cases of precursor B lymphoblastic lymphoma/leukemia (typically weak and variable in the latter), lymphocyte-predominant Hodgkin lymphoma, a subset of classical Hodgkin lymphoma, and some myelomas [characteristically myeloma with t(11;14)]. While regarded as a highly specific B-lineage associated marker, it has been rarely found in some mature T-cell lymphomas and carcinomas. Notably, any of these B-cell neoplasms may become CD20-negative following therapy with agents targeting CD20 (e.g. Rituximab), and staining for alternative B-cell markers (e.g. PAX5) is recommended for B-cell detection in such cases.
A formalin-fixed, paraffin-embedded (FFPE) tissue block is preferred specimen type or one (1) unbaked, unstained slide cut at 4-5 microns for H&E staining (required) and two to three (2-3) positively charged unstained slides cut at 3-4 microns for each test/antibody ordered.
Storage and Transport
Use cold pack during transport of paraffin blocks and unstained slides. Cold pack should not be placed in direct contact with the specimen during shipping
Specimen Rejection Criteria
Turn Around Time (TAT): 2-3 Days
CPT Codes*: 88341, 88342, 88360
*The CPT codes provided with our Test Descriptions are based on AMA guidelines and are for informational purposes only. Correct CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed.