CD5, a transmembrane protein, is found on most thymocytes and immature peripheral T-cells. It stains normal B-cells of mantle zone of spleen and lymph nodes, B-cells in peritoneal and pleural cavities, and almost all T-cells. In a fetus, most B-cells in spleen and cord blood are CD5 positive. It stains B-cell chronic lymphocytic leukemia/ small lymphocytic leukemia (CLL/SLL), mantle cell lymphoma (MCL), hairy cell leukemia (HCL), most T-malignancies, and most thymic carcinomas. CD5 is usually negative in spindle cell thymoma.
- A formalin-fixed, paraffin-embedded (FFPE) tissue block is preferred specimen type
- 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.
Use cold pack for transport. Make sure cold pack is not in direct contact with specimen.