Background: Oral lichen planus (OLP) is a chronic T-cell-mediated inflammatory disorder classified by the World Health Organization as a potentially malignant disorder. Diagnosis remains challenging due to clinical and histopathological overlap with other oral white lesions, including lichenoid reactions, frictional keratosis, and malignancy. Objectives: This systematic search with narrative review aimed to synthesize current diagnostic criteria, characterize key differential diagnoses, and provide an evidence-based diagnostic framework for clinicians. Methods: A comprehensive literature search was conducted across PubMed/MEDLINE, Scopus, Web of Science, and Embase through December 2025. Following a systematic screening process, eligible manuscripts were narratively summarized and a clinical case illustration was demonstrated. Results: Twenty-nine of 214 peer-reviewed studies (including systematic reviews, guidelines, and cohort studies) were summarized. Diagnostic standards have evolved toward the American Academy of Oral & Maxillofacial Pathology (AAOMP) 2016 criteria, which emphasize mandatory clinicopathological associations. Key differential diagnoses include reactive lesions (frictional keratosis), infectious conditions (chronic hyperplastic candidiasis), and other lichenoid patterns. Malignant transformation rates are approximately 1.43%, increasing to 5.13% in the presence of dysplasia, necessitating long-term surveillance. An 81-year-old case exemplifies the value of a stepwise diagnostic approach, in which initial management focuses on the elimination of local irritants and a period of clinical observation, followed by histopathological confirmation of oral lichen planus through biopsy when necessary. Conclusions: Accurate OLP diagnosis requires integrating clinical presentation with histopathological findings. A systematic diagnostic algorithm—incorporating local factor elimination, selective biopsy, and long-term monitoring—is essential to distinguish OLP from its mimics and manage the risk of malignant transformation effectively.
Rotaru et al. (Wed,) studied this question.