Three-dimensional analysis of intraepidermal nerve fibres and Langerhans cells in keloids with a focus on pruritus

Keloids are intractable dermato-fibrotic lesions that progressively expands from the primary lesion to the surrounding normal areas. In this study, we investigated uncontrollable pruritus in keloids and the association between keloid symptoms and pruritus using three-dimensional immunofluorescence for the analysis of nerve fibres and Langerhans cells in the anterior chest and ear keloids, and the analysis of messenger-RNA expression of substance P as a pruritus mediator. Nerve fibres infiltrating the epidermis were numerous in the periphery of the anterior chest keloids, where pruritus was reported, with some extending into the granular layer. However, there was no difference in Langerhans cells during pruritus, location or region of the keloid. Furthermore, we observed substance P gene expression in the periphery of the anterior chest keloids. Our observational study suggests an association between intractable pruritus in anterior keloid lesions, increased intraepidermal nerve fibre density, and elevated expression of Th2 cytokines and substance P.