What is perineural invasion?

Perineural invasion (PNI) refers to the presence of cancer cells surrounding or infiltrating the nerves within a tissue. It is often observed in various types of cancers, particularly in pancreatic, prostate, and head and neck cancers. PNI can indicate a more aggressive tumor behavior and may be associated with increased pain and a higher likelihood of metastasis. Its detection can influence treatment decisions and prognosis for patients.