IMMUNOHISTOCHEMISTRY, CD 20

What this test checks

Detects CD20, a protein expressed on mature B-lymphocytes. The primary marker for identifying B-cell lymphomas and the target for rituximab immunotherapy — one of the most important treatment advances in lymphoma.

Why do people get this test?

CD20 positivity identifies B-cell lymphomas that can be treated with rituximab (an anti-CD20 antibody) — dramatically improving outcomes. This is one of the most therapeutically important immunohistochemistry tests in oncology.

When you should consider this test

• When B-cell lymphoma is suspected
• When determining eligibility for rituximab-based therapy
• As the primary B-cell lymphoma marker in lymphoma diagnostic panels

How to prepare

No preparation needed — performed on biopsy or surgical tissue.