On a biopsy report
Perineural invasion (PNI)
Also written as PNI, Perineural infiltration, Neurotropism
What it means
Perineural invasion means the tumour has spread along and into nerve fibres. It is a finding the pathologist sees under the microscope, and it may be a sign of a poorer outlook.
Why it matters
Doctors note it as one more detail about how the tumour behaves. Your oncologist decides whether it changes treatment.
Ask your oncologist
"Does perineural invasion on my report change the treatment you are planning?"
From NCI Thesaurus (EVS): Perineural Invasion. Not medical advice: your oncologist decides.