Diagnostic Approach to Oral Lichen Planus and Oral Lichenoid Lesions: A Narrative Review

Oral lichen planus (OLP) and oral lichenoid lesions (OLLs) are common oral mucosal diseases that may be difficult to differentiate due to their clinical and histological similarities. Despite overlapping features, they require appropriate diagnosis given different etiologies, management strategies, and prognoses. OLP is a chronic, immune-mediated disease of unknown etiology, typically presenting as bilateral, symmetrical reticular lesions, erosions, or plaques on the buccal mucosa, gingiva, and tongue. In contrast, OLLs classically manifest as unilateral, asymmetrical lesions often associated with identifiable causes such as contact allergens, medications, or systemic diseases. Histologically, both OLP and OLLs may exhibit basal cell degeneration and a subepithelial lymphocytic infiltrate; however, OLLs often display deeper, mixed-cell, and perivascular inflammation. Clinically, OLP usually follows a chronic course, poses therapeutic challenges, and requires long-term surveillance due to its malignant transformation potential. OLLs may resolve following identification and elimination of the inciting factor; however, persistent OLLs may also carry a risk of malignant transformation and therefore warrant regular follow-up. Accurate diagnosis of OLP and OLLs requires a comprehensive approach that includes thorough medical history, clinical, histological, and immunological examinations, with novel non-invasive imaging techniques potentially offering adjunctive diagnostic support. This narrative review aims to synthesize current knowledge on OLP and OLLs, with particular emphasis on their key diagnostic features.