Comparative Analysis of the Tumour Mutational Burden in Erosive and Reticular Oral Lichen Planus.

Oral lichen planus (OLP) is a chronic inflammatory disease classified as an oral potentially malignant lesion. The erosive and reticular forms of OLP have the potential for malignant transformation, with no consistent data indicating that one form is more likely to undergo malignant transformation than the other. Tumour mutational burden (TMB) is a parameter that represents the number of somatic mutations in the DNA of neoplastic cells. This study aimed to compare TMB levels in the two primary clinical forms of OLP, the erosive and reticular sub-types. Next-generation sequencing of samples from 18 patients with OLP, including nine of each clinical form, was performed using the QIAseq Targeted DNA Human TMB Panel. Eight (44.4%) of the samples had a TMB ≤ 10 mutations/Mb, while 10 (55.6%) had a TMB of zero. No significant difference was observed between the erosive and reticular forms of OLP. A maximum of two somatic variations per sample was identified, involving genes associated with immune response (PTPRD, PSMA6 and CD274) and tumour suppression (PALB2, ATRX and BRCA2). Although these data suggest that genetic mutational events occur similarly in erosive and reticular OLP, further molecular studies are required to confirm the findings.