Pan-TRK immunohistochemistry

A pathologist applies antibodies to a tumour tissue section. If the target protein is present, the antibody can create a visible staining pattern under a microscope. “Pan-TRK” refers to a stain designed to recognise proteins made by several TRK genes, rather than one specific gene. The location and strength of staining, along with the tumour type, help the pathologist interpret the finding.

A positive stain does not by itself prove an NTRK fusion, and a negative result does not answer every molecular question. Other proteins or background staining can affect interpretation. Learn more about [Immunohistochemistry](/technology/immunohistochemistry/) and [Biopsy](/treatments/diagnostics-and-staging/biopsy/).

Ask whether the result is reported as positive, negative, weak, focal or equivocal, and what that wording means for your sample. If the stain suggests TRK expression, the team may recommend molecular testing that examines the tumour's DNA or RNA for an NTRK fusion. The available tissue, tumour type and laboratory method can influence the next step.

Keep the pathology report with your other records and ask who will explain it. Treatment decisions should consider the complete diagnosis, staging information, symptoms and your preferences rather than one stain alone.

This laboratory test usually does not cause new symptoms because it is performed on tissue already collected. Contact your clinical team if you are waiting for a result and need clarification about timing, if a biopsy site becomes increasingly red or painful, or if bleeding, drainage or fever develops after a procedure. Seek urgent help for heavy bleeding, severe breathing difficulty or collapse.

Was pan-TRK staining performed on my tumour sample? What pattern was seen? Is confirmatory NTRK fusion testing appropriate? Is there enough tissue for further testing? How could the result affect treatment discussions?