Incidence of Pseudoepitheliomatous Hyperplasia in Oral Granular Cell Tumors of Adults: An Independent Retrospective Analysis Utilizing a Novel Definition

<b>Background:</b> As most biopsy specimens are diagnosed by interpretation of glass slides, the diagnostic process is heavily reliant on subjective interpretation. Granular cell tumors have a widely reported incidence of a pathological phenomenon termed pseudoepitheliomatous hyperplasia. <b>Aim:</b> The study's primary focus was to determine the incidence of pseudoepitheliomatous hyperplasia in granular cell tumors in adults using a novel definition. <b>Methods:</b> A review of the existing literature provided a foundation for a novel definition of pseudoepitheliomatous hyperplasia. Two oral pathology laboratories' archived material were queried to yield 70 specimens matching inclusion criteria. Two board certified Oral and Maxillofacial Pathologists were employed as observers, calibrated on the novel definition using control specimens, and then a blind review was performed. Statistical analyses were performed via Kappa statistical agreement and Fischer's 2-way exact tests. <b>Results:</b> Use of the novel definition resulted in agreement in 97.4% of specimens. The Kappa agreement was 0.939 with a standard error of 0.043 and a 95% confidence interval from 0.856 to 1.0. Landis and Koch's standards for strength of agreement was "almost perfect." Pseudoepitheliomatous hyperplasia was found at a rate of 36.8%. Women made up 79.4% of the study population and the average age was 45 years. Intraorally 91.8% of lesions occurred on the tongue and buccal mucosa. And 93.30% of lateral tongue granular cell tumors occurred in women. <b>Conclusion:</b> Using a definition prior to evaluating subjective histologic criteria resulted in "almost perfect" interobserver statistical reliability. Our definition of pseudoepitheliomatous hyperplasia proved to be reliable and should be further tested.