Interobserver Variation Among Pathologists in Evaluating Perineural Invasion for Oral Squamous Cell Carcinoma

The aims of this study are as follows: (1) to assess variations among pathologists in evaluating perineural invasion (PNI) in oral squamous cell carcinoma (OSCC), (2) to survey PNI criteria used by pathologists and how they came to adopt those criteria. An electronic survey was sent to 363 oral and/or surgical pathologists. Eligibility criteria included pathology board certification. The survey participants were asked to rate whether PNI was present, absent, or uncertain for 15 provided photomicrographs, which depicted various types of tumor-nerve relationships without excessive desmoplasia or lymphocytic host response. The survey obtained information regarding demographics, whether PNI criteria were taught during residency, criteria used by participants to evaluate PNI, how the participants developed their criteria, and agreement with six proposed PNI definitions. 88 pathologists completed the survey. The participants included 47 males and 41 females, with average age = 49 years and average practice experience = 17 years. Practice settings included dental school (40 %), medical school (36 %), private pathology lab (13 %), and other (11 %). Agreement between participants in rating PNI status for the provided images was fair (kappa=.38, 95 % CI.37-.39). 56 % of respondents indicated that they were taught PNI criteria during residency training. The basis for criteria currently used by participants included residency training (n = 42), published literature (n = 29), and own experience/views (n = 32). Agreement regarding six proposed PNI definitions was slight (kappa=.10, 95 % CI.08-.11). In conclusion, interobserver agreement in assessing PNI status was fair. Our results suggest that more widely accepted, objective, and reproducible criteria are needed for evaluating PNI in OSCC.