IMMUNOHISTOCHEMISTRY, CD 23

What this test checks

Detects CD23, a marker expressed on follicular dendritic cells and chronic lymphocytic leukaemia (CLL) cells. Used to identify CLL and distinguish it from mantle cell lymphoma (MCL).

Why do people get this test?

CLL and MCL can look identical under the microscope but require very different treatments. CD23 positivity supports CLL and argues against MCL — a critical distinction that changes chemotherapy choice entirely.

When you should consider this test

• When classifying small B-cell lymphomas (CLL vs. mantle cell lymphoma)
• When evaluating B-cell lymphoproliferative disorders
• As part of small lymphocytic lymphoma/CLL diagnostic panel

How to prepare

No preparation needed — performed on biopsy or surgical tissue.