Measuring the Depth of Perineural Invasion in Cutaneous Squamous Cell Carcinoma: Implications on Biopsy Technique.

Background: Perineural invasion (PNI) is a high-risk feature of cutaneous squamous cell carcinoma (CSCC). Depths at which PNI occurs are unknown.

Objective: To determine the most superficial depth at which PNI occurs in CSCC and stratify by tumor clinical diameter and body location.