Pruritus in Keloid Scars: Mechanisms and Treatments

Abstract

Keloids are scars that extend beyond the margins of an insulting cutaneous injury. Keloids are often thought to be primarily a cosmetic issue, as they are typically quite raised and pigmented. However, these scars also present with functional symptoms of pruritus and pain that significantly impact quality of life. The symptom of pruritus is frequently overlooked by dermatologists, and treatments are often primarily focused on the gross appearance of the scar. This review describes the prevalence and importance of pruritus in keloids. In addition, the putative mechanisms underlying the development of keloid pruritus, which include neuronal and immunological mechanisms, are discussed. Furthermore, this review describes keloid treatments that have been shown to reduce pruritus, treatments that specifically target the itch, and emerging therapies.

Fig. 1

A putative mechanism of the mediators of pruritus in keloids and the effect of different treatment modalities. Green line: activation; red line: inhibition; 5-FU: 5- fluorouracil; BTA: botulinum toxin A; CaV: voltage gated calcium channel; CTGF: connective tissue growth factor; TGF-b: GABA: gamma aminobutyric acid; HBOT: hyperbaric oxygen therapy; IL: interleukin; Ra: receptor alpha; KAL: ketamine amitriptyline lidocaine; M2: type 2 macrophage; MOR: mu opioid receptor; NaV: voltage gated sodium channel; NGF: nerve growth factor; NMDA: N-methyl-D-aspartate; OSMRb: oncostatin M receptor beta; PDL: pulse dye laser; SP: substance P; TGF-b: transforming growth factor beta; Th2: type 2 helper T cell; TRP: transient receptor potential; TRPV: transient receptor potential vanilloid.