Image-based DNA ploidy analysis aids prediction of malignant transformation in oral lichen planus.

OBJECTIVES To investigate the potential of image-based DNA ploidy analysis to predict malignant transformation in patients with oral lichen planus (OLP). STUDY DESIGN DNA ploidy analysis was performed on biopsy samples from 14 patients with OLP who underwent malignant transformation. As controls, 42 OLP lesions showing unusual clinical features suggesting a transformation risk and 68 samples of clinically and histologically typical OLP were included. Cases with dysplasia on initial biopsy were excluded. Eighty fibroepithelial polyps acted as methodologic controls. Epithelial nuclei were isolated from formalin-fixed paraffin embedded biopsy samples and monolayers stained with Feulgen for automated image cytometry to establish DNA content. Ploidy status was correlated to outcome using Kaplan-Meier analysis and log-rank Mantel-Cox tests. RESULTS All controls and typical OLP were diploid and none underwent malignant transformation in mean follow-up of 14 years (10-18 years). One unusual OLP developed carcinoma and all were diploid. The 14 patients with transformation developed 21 carcinomas. In the 11 patients who had a prior biopsy, 4 were aneuploid. CONCLUSIONS DNA ploidy analysis predicted malignant transformation in more than one third (36.4%) of patients with OLP with a preceding biopsy (n = 11). This premalignant nature could not have been diagnosed clinically or by histologic dysplasia assessment.