Characterization of different tissue changes in normal, betel chewers, potentially malignant lesions, conditions and oral squamous cell carcinoma using reflectance confocal microscopy: correlation with routine histopathology

Abstract

The goal of this study was to characterize the features of normal mucosa, mucosa in betel chewers and smokers, potentially malignant lesions and squamous cell carcinoma of oral mucosa using reflectance confocal microscopy. Oral cavity biopsies were acquired from 25 patients from College of Dental Surgery, Saveetha University who underwent screening for suspected lesions of Oral precancer and Oral cancer along with normal patients who underwent impaction. Biopsies were acquired from the clinically suspicious area and immediately placed in Dulbecco modified eagles growth medium (DMEM). Reflectance confocal images were obtained at multiple image plane depths from biopsies within 6h of excision. After imaging, biopsies were fixed in 10% formalin and submitted for routine histopathological examination by an experienced oral and maxillofacial pathologist. Reflectance confocal images were compared with histological images from the same sample to determine the tissue features which contribute to early cellular changes, image contrast and early diagnosis. The confocal images were obtained to a depth of up to 150 microns on intact biopsy specimens and subsequent 3-dimensional images, keratin thickness measurements, cell measurements, cell density analysis and graphical representations were performed using Leica image analysis software. In normal mucosa keratin deposition were seen as alternating dark and bright stacks and in different cell layers the nuclei were seen as disks of varying intensities. In pre-cancerous lesions the keratin thickness and cell nuclear density were found to be increased when compared to normal controls. In OSMF cases confocal images of fibrosis show scattering from individual fibres as hyperdense areas. Oral squamous cell carcinoma cases demonstrated extensive variations in cell size, nuclear size and nuclear morphology. At cellular level, dysplastic features like increased nuclear density, increased nuclear cytoplasmic ratio, nuclear and cellular pleomorphism with loss of cohesiveness were identified in all five cases. Our results support the potential of reflectance confocal microscopy to play a significant role in clinical evaluations of oral lesions, early diagnosis of potentially malignant and malignant oral lesions and real time identification of tumour margins.