Oral potentially malignant disorders: a practical review for the diagnostic pathologist

This article provides a broad overview of oral potentially malignant disorders (OPMD) and associated entities. The review opens with an update on the terminology surrounding OPMD before summarizing the lesions and conditions currently recognized as OPMD by the World Health Organization (WHO). Approaches to diagnosing oral epithelial dysplasia (OED) are discussed in the context of the WHO's recently modified architectural and cytological criteria for OED. The spectrum of reactive epithelial changes – which may mimic OED - is explored for comparison. The review then focuses on four significant OPMD - proliferative verrucous leukoplakia, oral submucous fibrosis, HPV-associated OED, and oral lichen planus – with clinical and histopathological examples. Next, potential pitfalls - non-preneoplastic lesions that can mimic OPMD clinically and histopathologically - are highlighted; these include chronic hyperplastic candidosis, verruciform xanthoma, granular cell tumour, and hairy leukoplakia. Molecular tests for identifying and stratifying OPMD are commented on briefly as - to date - histopathology remains the most reliable prognosticator. Clinicopathological correlation is critical to accurate histopathological diagnosis, risk stratification, and clinical management. The review closes by highlighting clinical features – e.g., associated redness – indicative of high risk.