What should you know about LCA immunohistochemistry?

LCA usually refers to leukocyte common antigen, also known as CD45. In immunohistochemistry, a laboratory applies an antibody to prepared tissue. If the target marker is present, the tissue cells show a detectable staining pattern. A pathologist compares that result with the cells' appearance, the tissue structure, and other stains.

A positive LCA result supports the presence of cells from the white-blood-cell family, but it does not by itself name a lymphoma, leukaemia, infection, or another condition. Some abnormal cells may show weak, variable, or absent staining. The full interpretation depends on the biopsy, clinical information, imaging, and a panel of markers rather than one result alone.

Ask whether the sample was adequate, which cells stained, and which additional markers are being used. Confirm whether the report is preliminary or final and when the treating team expects to discuss it. You can read about the laboratory method in [Immunohistochemistry](/technology/immunohistochemistry/) and the tissue procedure in [Biopsy](/treatments/diagnostics-and-staging/biopsy/).

Bring the pathology report to the appointment and ask for unfamiliar terms to be explained. Do not interpret an isolated positive or negative stain without the rest of the report.

The stain itself usually does not cause symptoms because it is performed on tissue already collected. Seek care for biopsy-site bleeding that does not settle, increasing redness or swelling, drainage, fever, worsening pain, or feeling faint. Contact the oncology or pathology team if a result is unclear and you do not know who will explain the next step.

What does LCA staining show in my sample? Which cells are positive or negative? What other stains were ordered, and why? Is the diagnosis final? Could the sample need further review or testing? How does this result affect the next appointment or treatment discussion?