Malignant transformation of verrucous oral potentially malignant disorders at a tertiary referral centre: A retrospective cohort study.

OBJECTIVES

Verrucous hyperplasia (VH) is a histological feature of uncertain malignant potential seen in both conventional leukoplakia and proliferative verrucous leukoplakia (PVL). This study compared the clinical presentation and malignant transformation rates of unifocal VH and PVL and assessed whether baseline features predict malignant transformation.

METHODS

A retrospective cohort study was conducted of patients with histologically confirmed VH with a minimum follow-up of 5 years. Cases were classified as PVL if lesions were multifocal, or VH if unifocal. Clinicopathological features were compared between diagnoses. Malignant transformation to oral squamous cell carcinoma (OSCC) was assessed using Kaplan-Meier survival analyses, stratified odds ratios and time-dependent Cox regression models.

RESULTS

81 patients were included with a median follow-up of 121 months. 21 patients developed multifocal lesions consistent with PVL. Patients with PVL were more likely to present with baseline lymphocytic banding (p = 0.007), but without baseline oral epithelial dysplasia (OED; p = 0.003) or verrucous architecture (p < 0.001). Overall, 30.9% patients developed OSCC. Transformation occurred in 26.7% of VH and 42.9% of PVL cases. Baseline OED was associated with increased early transformation hazard but reduced late risk (interaction p = 0.037), whereas baseline lymphocytic banding demonstrated a strong association with late malignant transformation (OR 15.37, p = 0.003).

CONCLUSIONS

Transformation rates of verrucous oral potentially malignant disorders exceed those expected for conventional leukoplakia. PVL often lacks OED and verrucous architecture at presentation, limiting early recognition using conventional grading systems. Lymphocytic banding may represent an independent marker of late malignant risk and could refine risk stratification beyond OED grading alone.