perineural invasion
Also written as: PNI — perineural invasion
Tumor cell infiltration along nerve sheaths, indicating aggressive disease with potential for local recurrence.
Full Definition
Perineural invasion (PNI) describes the pathologic finding of tumor cells tracking along or around nerve fibers and within the perineural space. In urologic oncology, PNI is most commonly observed in prostate cancer and is associated with higher grade tumors, extracapsular extension, and increased risk of biochemical recurrence following radical prostatectomy. This histologic feature is routinely assessed and reported in surgical specimens. The presence of perineural invasion may influence decisions regarding adjuvant radiation therapy and surveillance intensity.
Usage
Usage note: Commonly abbreviated as PNI. Should not be confused with lymphovascular invasion, which involves blood or lymphatic vessels.
In Context
- "Extensive perineural invasion was noted throughout the prostate specimen, raising concern for aggressive disease." — Pathology report
- "The presence of perineural invasion prompted discussion of adjuvant radiation therapy at the tumor board." — Multidisciplinary conference note