Abnormal p53 Immunohistochemical Patterns Shed Light on the Aggressiveness of Oral Epithelial Dysplasia

Abstract

The diagnosis of oral epithelial dysplasia is based on the degree of architectural and cytologic atypia in the squamous epithelium. The conventional grading system of mild, moderate, and severe dysplasia is considered by many the gold standard in predicting the risk of malignant transformation. Unfortunately, some low-grade lesions, with or without dysplasia, progress to squamous cell carcinoma (SCC) in short periods. As a result, we are proposing a new approach to characterize oral dysplastic lesions that will help identify lesions at high risk for malignant transformation. We included a total of 203 cases of oral epithelial dysplasia, proliferative verrucous leukoplakia, lichenoid, and commonly observed mucosal reactive lesions to evaluate their p53 immunohistochemical (IHC) staining patterns. We identified 4 wild-type patterns, including scattered basal, patchy basal/parabasal, null-like/basal sparing, mid-epithelial/basal sparing, and 3 abnormal p53 patterns, including overexpression basal/parabasal only, overexpression basal/parabasal to diffuse, and null. All cases of lichenoid and reactive lesions exhibited scattered basal or patchy basal/parabasal patterns, whereas human papillomavirus-associated oral epithelial dysplasia demonstrated null-like/basal sparing or mid-epithelial/basal sparing patterns. Of the oral epithelial dysplasia cases, 42.5% (51/120) demonstrated an abnormal p53 IHC pattern. p53 abnormal oral epithelial dysplasia was significantly more likely to progress to invasive SCC when compared to p53 wild-type oral epithelial dysplasia (21.6% vs 0%, P < .0001). Furthermore, p53 abnormal oral epithelial dysplasia was more likely to have dyskeratosis and/or acantholysis (98.0% vs 43.5%, P < .0001). We propose the term p53 abnormal oral epithelial dysplasia to highlight the importance of utilizing p53 IHC stain to recognize lesions that are at high risk of progression to invasive disease, irrespective of the histologic grade, and propose that these lesions should not be graded using the conventional grading system to avoid delayed management.