Methodology
Immunohistochemistry (IHC)
Test Description
Normal cell expression of CD20 is found on most B-cells (after CD19 and CD10 expression, before CD21/22 expression and surface immunoglobulin expression) and expression is retained on mature B-cells until plasma cell development, as well as ollicular dendritic cells. In diseased cells, there is positive staining on most B-cell lymphomas, come pre-acute B lymphoblastic leukemia/ lymphoblastic lymphoma (B-ALL/LBL); lymphocyte predominant Hodgkin lymphoma, dimly expressed in T-cells (benign and neoplastic), and spindle cell thymomas. Rixtuximab treated patients may lose CD20 positivity in B cell lymphomas.
Specimen Requirements
- A formalin-fixed, paraffin-embedded (FFPE) tissue block is preferred specimen type
or - One (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 ordered
- Block and slide identifiers should be clearly written and match exactly with the specimen ID and specimen labeling as noted on the requisition.
Storage & Transportation
Use cold pack for transport. Make sure cold pack is not in direct contact with specimen.
CPT Code(s)*
88342 x 1 or 88341 x 1
Turnaround Time
24 hours
Level of Service
Stain Only
New York Approved
Yes