Molecular classification of autofluorescence excision margins in oral potentially malignant disorders.

OBJECTIVE: To define molecular differences between autofluorescence and white light defined excision margins in oral potentially malignant disorders (OPMD) using transcriptome expression profiles. MATERIALS AND METHODS: Excisional biopsy specimens were taken from 11 patients at three different sites for each lesion: centre, white light margin and autofluorescence margin. The lesions were diagnosed histopathologically as oral epithelial dysplasia, oral lichenoid dysplasia, oral lichen planus or other. Transcriptome analysis was performed by RNA sequencing, hierarchical clustering, differential expression and biological pathway analysis. RESULTS: For hierarchical clustering, the samples broadly clustered according to histology rather than the margins with lichenoid samples clustering together. Differential expression analysis showed that independent of histology, there was greater molecular dysregulation between the lesion centre and autofluorescence margin compared to the lesion centre and white light margin. Furthermore, the autofluorescence and white light margins were molecularly distinct, indicating the white light margins harboured abnormality. CONCLUSION: Our results indicate that the molecular profile of OPMD changes with divergence away from the centre of the lesion, and that autofluorescence determined margins are superior to the white light margin in achieving a clear molecular margin when excising an OPMD.

Patterns of differentially expressed genes in oral mucosal lesions visualised under autofluorescence (VELscope(™) ).

OBJECTIVES: We aimed to elucidate the molecular pathways associated with fluorescence properties of oral potentially malignant disorders (OPMD) visualised under direct tissue autofluorescence (VELscope(™)). MATERIALS AND METHODS: Forty-two oral mucosal biopsies correlated with clinical fluorescence characteristics were categorised based on histopathological diagnosis. Four oral squamous cell carcinoma (OSCC), 15 oral epithelial dysplasia (OED), nine oral lichen planus (OLP) and 14 oral epithelial hyperplasia (OEH) presenting with three fluorescence patterns including retained fluorescence (RF), loss of fluorescence (LAF) with blanching (LB) and LAF with no blanching (LNB) were assessed. Relative gene expression was measured through RNA sequencing. RESULTS: Although each lesion type had a specific set of histology-related differentially expressed genes (DEGs), all tested samples shared a number of DEGs, and we could not identify a discriminatory component between histological groups. Gene ontology enrichment revealed LAF in OEH was mostly due to changes in inflammation, cell cycle regulation and apoptosis, while in OED was due to inflammation, angiogenesis and extracellular matrix remodelling. Inflammatory reactions were associated with diascopic fluorescence (DF) for both OEH and OED. CONCLUSION: Uncovering the molecular mechanisms underlying LAF and DF may lead to reduction in the number of false-positive and false-negative findings and improve the efficacy and utility of VELscope(™).