Itch in Lichen Simplex Chronicus Is Associated with Localized Small Fiber Neuropathy

Abstract

Lichen simplex chronicus (LSC) is a common pruritic condition of unknown pathophysiology. The sensory innervation of the skin consists of a dermal plexus formed by myelinated and unmyelinated fibers. The epidermis only contains unmyelinated fibers, which signal temperature, pain, and/or itch (Ikoma et al., 2006). Intraepidermal fibers can be visualized using the marker PGP 9.5, a ubiquitin C-terminal hydrolase, which is abundantly present in the nervous system (Lauria et al., 2010). Studies of conditions associated with chronic itch have reported increased or decreased intraepidermal nerve fiber density (prurigo nodularis [Johansson et al., 2000; Schuhknecht et al., 2011], amyloidosis [Tey et al., 2016], or epidermolysis bullosa [von Bischhoffshausen et al., 2017]).