Optical diagnosis of oral lichen planus: A clinical study on the use of autofluorescence spectroscopy combined with multivariate analysis

Abstract

Oral lichen planus (OLP) is a chronic mucocutaneous inflammatory condition of stratified squamous epithelia. OLP is a potentially malignant condition in oral mucosa. Patients with OLP have an increased risk of developing squamous cell carcinoma. Therefore an early and accurate diagnosis is necessary to avoid further damage to the oral mucosa. Biopsy followed by histopathological examination is the gold standard for the diagnosis of oral mucosal lesions including OLP. But this invasive procedure is traumatic and time consuming with limited statistical confidence level. Autofluorescence spectroscopy (AFS) has recently emerged as a potential tool to evaluate the biochemical changes associated with oral cavity disorders. In this study, we used AFS to differentiate the oral cavity tissue of 20 OLP patients from that of 16 normal volunteers. Spectra from oral mucosa were acquired at 280, 320 and 410 nm excitation wavelengths which correspond to the excitation energy of major endogenous fluorophores. Normalized spectral data at 320 nm excitation showed significant increase in the intensity of collagen peak for OLP. Optical redox ratio and total hemoglobin concentration estimated from the spectral data revealed significant increase and decrease respectively in OLP and normal patients. Principal component analysis followed by linear discriminant analysis (PCA-LDA) provided sensitivity and specificity of 71 and 80%, 80 and 90%, and 72 and 75% respectively for 280, 320 and 410 nm excited spectral datasets. Meanwhile, partial least square discriminant analysis (PLS-DA) provided sensitivity and specificity of 69 and 77%, 78 and 91% and 73 and 78.13% respectively for 280, 320 and 410 nm excited spectral datasets. From the results, it is concluded that AFS is an efficient tool for the non invasive diagnosis of OLP, with 320 nm light identified as the best wavelength for excitation.