A cell surface-associated protein expressed during the middle to later stages of B cell maturation in the bone marrow, and all normal mature B cells. It is expressed on mature B-cells until plasma cell development and on ollicular dendritic cells. In diseased cells, most B-cell lymphomas, some pre-acute B lymphoblastic leukemia/lymphoblastic lymphoma, lymphocyte predominant Hodgkin lymphomas are positively stained and it is dimly expressed in both benign and neoplastic T-cells and spindle cell thyomas. It is the target of the therapeutic antibody Rituxan and patients may lose CD20 positivity in B cell lymphomas.
A formalin-fixed, paraffin-embedded (FFPE) tissue block is preferred specimen typeorOne (1) unbaked, unstained slide for H&E staining (required) and two to three (2-3) positively charged unstained slides (all cut at 4-5 microns) for each test/antibody orderedBlock and slide identifiers should be clearly written and match exactly with the specimen ID and specimen labeling as noted on the requisition.
Use cold pack for transport. Make sure cold pack is not in direct contact with specimen.