Digital Characterization of Clinical Subtypes of Oral Lichen Planus by Means of a Semi-Automated Morphometric Analysis: A Retrospective Observational Study.

Background: Oral lichen planus (OLP) is a chronic inflammatory disease of unknown etiology. Its clinical and histopathological diagnosis remains challenging due to the variability of its manifestations and the subjectivity involved in interpretation. Objective: This study aimed to examine the relationship between different clinical phenotypes of OLP (reticular, erosive, and mixed) and histomorphological features obtained through digital analysis with semi-automated segmentation. Methods: A retrospective review of 100 OLP cases was conducted. Clinically, the samples were classified into three groups: 68 reticular, 16 erosive, and 16 mixed. Epithelial and connective tissue parameters were evaluated on hematoxylin-eosin-stained sections using digital tools and segmentation algorithms. Results: The erosive phenotype showed greater irregularity of suprabasal nuclei (p = 0.008) and a higher basal nucleus-to-cytoplasm ratio (p = 0.02). No significant differences were found among the groups regarding epithelial thickness or lymphocyte density (p > 0.05). Conclusions: The cellular alterations observed in the erosive subtype may reflect higher tissue activity and provide additional elements for its characterization. Digital morphometric analysis appears to be a promising complementary tool, although further studies are needed to confirm its diagnostic applicability.