Allelic imbalance in oral lichen planus and assessment of its classification as a premalignant condition

Abstract

OLP is a relatively common immune-mediated mucosal condition with a predilection for middle-aged women. Although classified as a premalignant condition, this classification remains controversial. Using stringent diagnostic criteria, some authors have found that OLP patients are not at increased risk for oral SCC. Credible but limited genetic evidence also indicates that epithelial tissues from OLP patients diagnosed using stringent criteria differs from premalignant or malignant oral lesions but is similar to epithelium from benign oral lesions. To further investigate this genetic line of evidence, biopsy specimens diagnosed as fibroma, OLP, low-grade dysplasia, high-grade dysplasia, and SCC were retrieved from the archives of the Oral Pathology Consultants at the Ohio State University. Using laser capture microdissection, tissue of interest was captured from each case and DNA subsequently extracted. Fluorescently labeled PCR primers were used to amplify DNA at 3 tumor suppressor gene loci (3p14.2, 9p21, and 17p13) and evaluated for LOH or microsatellite instability (MSI). OLP was found to be significantly different from low-grade dysplasia, high-grade dysplasia, and SCC when LOH/MSI was found at more than 1 loci (P = .011, P = .032, P = .003), but not different from benign fibromas (P = .395). In agreement with previous studies, well-documented cases of OLP diagnosed using stringent criteria exhibit a genetic profile more similar to a benign or reactive process than a premalignant/malignant one. These findings do not support the classification of OLP as a premalignant condition.

Fig. 1

Examples of OLP (A), low-grade dysplasia (B), and SCC (C) before and after laser capture (hematoxylin-eosin stain; magnification ×10).

Fig. 2

Examples of (A) electropherogram demonstrating a normal pattern (OLP case # 15, marker TP53), (B) electropherogram demonstrating MSI pattern (SCC # 12, marker D9S1748), and (C) electropherogram demonstrating LOH pattern (SCC case # 11, marker D3S1300). Note: x-axis values denote size in base pairs; y-axis denotes fluorescence intensity.