Lichenoid and Granulomatous Stomatitis: Three Additional Cases and Detailed Immunohistochemical Analysis

BACKGROUND: Lichenoid and granulomatous stomatitis (LGS) is a rare condition, with clinicopathological features resembling lichenoid and granulomatous dermatitis. Despite increasing reports, its etiology remains unclear and detailed immunohistochemical (IHC) studies are lacking. METHODS: We analyzed three new LGS cases, comparatively assessed with six cases each of oral lichen planus (OLP), oral lichenoid lesion (OLL), and oral leukoplakia (OL) showing lichenoid infiltrate. Histopathologic patterns were classified using the modified Magro & Crowson system, and IHC analysis included lymphocyte subsets, macrophages, and dendritic cells. Statistical comparisons were performed using Kruskal-Wallis with Dunn's post hoc test. RESULTS: All LGS cases showed lymphohistiocytic infiltrates, microgranulomas, and perivascular/perineural lymphohistiocytic aggregates. IHC analysis revealed that LGS showed a significantly larger amount of macrophages (CD11c+/CD68+/CD163+) indicating M1/M2 equilibrium, CD3+ and CD8+ T-cells, FOXP3+ regulatory T-cells, and submucosal dendritic cells (FXIIIA+/CD209+) when compared to OLP/OLL/OL. Langerhans cells (CD1a+/CD207+) were similarly observed, whereas CD20+ B-cells were scarce. CONCLUSIONS: This study provides the first comprehensive IHC analysis of LGS, highlighting distinctive macrophage, T-cell, and dendritic cell profiles. These findings contribute to understanding LGS pathogenesis, support its diagnostic distinction, and suggest potential immunotherapeutic targets.