PLAP immunohistochemistry: what to know

PLAP stands for placental alkaline phosphatase, a protein that can be present in certain normal tissues and some tumours. In immunohistochemistry, a laboratory applies an antibody to a tissue section. If the target is present, a visible staining pattern may appear in the relevant cells.

Pathologists do not interpret PLAP in isolation. They consider where the stain is located, how strong or widespread it is, the cell shape and arrangement, and the results of other markers. The clinical history, scans, blood tests, and the tissue obtained through biopsy also matter. A positive PLAP stain can support a diagnostic possibility, but it does not by itself identify one specific cancer.

Ask for the exact wording of the report and whether PLAP was diffuse, focal, membranous, or otherwise patterned. Ask which additional stains were used to narrow the diagnosis and whether the specimen was adequate. Keep the pathology report with your imaging and clinic letters, since later specialists may need to review the complete panel rather than one stain.

A biopsy is the procedure that obtains tissue; immunohistochemistry is the laboratory examination performed on a prepared tissue section. These terms describe different parts of the diagnostic process.

The stain result itself does not cause symptoms or determine urgency. Contact your care team promptly for new severe pain, heavy bleeding, fever, confusion, breathing difficulty, or rapidly worsening symptoms related to the condition being investigated. After a biopsy, follow the procedure-specific instructions for wound changes, bleeding, or infection.

What does the PLAP pattern show in my specimen? Which other markers were tested? What diagnoses are being considered, and how do the scan and clinical findings fit? Is a second pathology review or more tissue needed?