The Distribution of Innervation and Immune Cell Infiltration Is Different in Genital and Extragenital Variants of Lichen Sclerosus

Lichen sclerosus (LS) is a progressive skin disease that is characterized by chronic inflammation of either genital or extragenital skin, and it disproportionately affects women. We analyzed the distribution of nerve fibers, vanilloid receptors, cell proliferation, mast cells and macrophages in genital and extragenital LS samples, as well as in healthy skin, by using immunohistochemistry. The total amount of intraepidermal nerve fibers was lower in LS samples compared to healthy controls, while the total amount of subepidermal nerve fibers and calcitonin gene-related peptide (CGRP) positive fibers was higher in genital LS samples compared to both extragenital LS and healthy controls. Cell proliferation, macrophage and mast cell density were increased in LS samples compared to healthy controls. Genital LS had a higher macrophage density compared to the extragenital variant. Mast cell distribution significantly differed between genital and extragenital LS samples, even though their total mast cell densities were similar. These findings could explain the differences between pruritic symptoms of genital and extragenital LS and provide targets for the research of novel therapeutic strategies for LS management.