• All IHC stains will include a positive control tissue

• CD5 is useful in a panel of immunostains (on frozen and/or paraffin sections) to differentiate between various types of low grade B-cell lymphoma (CLL/WDLL and IDL/mantle cell lymphomas are positive)
• CD5 should always be interpreted in conjunction with other T-cell markers and considered as positive (on B-cells) if the staining is present in areas otherwise negative for other T-cell antigens
• The absence of CD5 reactivity in the above mentioned small cell lymphocytic malignancies significantly correlated with extra-nodal presentation
• CD5 may be helpful in the differential of mediastinal tumors; thymic carcinomas are positive, squamous cell carcinomas are negative

Submit a formalin-fixed, paraffin embedded tissue block

Formalin-fixed, paraffin embedded (FFPE) tissue block

FFPE tissue section mounted on a charged, unstained slide

Ambient (preferred)

• Unlabeled/mislabeled block
• Insufficient tissue
• Slides broken beyond repair

Immunohistochemical staining and microscopic examination

If requested, an interpretive report will be provided

Specifications

• CD5 is a 67 kD cell membrane glycoprotein
• CD5 reacts with normal T cells, a small subset of normal B lymphocytes and neoplastic B lymphocytes in certain low grade B cell lymphomas
• CD5 can also react with mesotheliomas, but shows intracytoplasmic staining rather than cell membrane based staining

 
Staining pattern

• Cell membrane (intracytoplasmic staining seen in mesotheliomas)

References

1. Arber DA et al: CD5: a review. Appl Immunohistochemistry. 1995; 3:1-22.
2. Tjateyama H et al: Immunoreactivity of a new CD5 antibody with normal epithelium and malignant tumors including thymic carcinoma. Am J Clin Pathol 1999; 111:235-240.