IMMUNOHISTOCHEMISTRY, CD 79A

What this test checks

Detects CD79a, a protein expressed on B-lymphocytes throughout their development. Used to confirm B-cell lineage in lymphomas and leukaemias, especially when CD20 staining is negative after treatment.

Why do people get this test?

CD79a remains expressed even after anti-CD20 therapy (rituximab), making it valuable for confirming B-cell origin in patients who have been treated. It ensures lymphoma classification is not affected by prior treatment.

When you should consider this test

• When confirming B-cell lymphoma in previously treated patients
• When classifying lymphomas — particularly plasma cell or precursor B-cell types
• As part of B-cell lineage confirmation panel

How to prepare

No preparation needed — performed on biopsy or surgical tissue.