Lichen Simplex Chronicus Itch: An Update

Abstract

Lichen simplex chronicus is a form of chronic localized pruritus with a secondary dermatitis, and one of the most common types of chronic itch conditions, estimated to affect more than 10% of the general population. However, despite its prevalence and burden, there has been limited research into the pathogenesis and aetiology of lichen simplex chronicus, which, historically, made it a challenging condition to treat. In recent years, our understanding of this condition, along with that of pruritus and the itch-scratch cycle, has increased greatly, enabling a substantial increase in treatment options. In addition, there are several new promising treatments currently in development and trials. This article discusses the definition, epidemiology, clinical characteristics, pathophysiology, and current therapeutic options for lichen simplex chronicus, in order to highlight recent advancements in this field.

Fig. 1

Bilateral lichen simplex chronicus plaques on the flexural surfaces of the feet.

Fig. 2

Lichen simplex chronicus of the posterior scalp shows irregular acanthosis with hypergranulosis and pronounced hyperkeratosis reminiscent of the acral skin. There is an increased number of fibroblasts in the upper dermis, and mild perivascular lymphocytic infiltrate (haematoxylin and eosin, ×10). Credit to and permission obtained to publish from Dr Mariya Miteva.

Fig. 3

Pathophysiology of lichen simplex chronicus and its therapeutic targets. AMPs: antimicrobial peptides; JAK-STAT: janus kinase-signal transducer and activator of transcription; IL: interleukin; PAR-2: protease-activated receptor 2; SSRIs: selective serotonin reuptake inhibitors; TENS: transcutaneous electrical nerve stimulation; Th: T-helper cell; TRPV: transient receptor potential vanilloid; 5-HT: serotonin.