Itching for an Answer: A Review of Potential Mechanisms of Scalp Itch in Psoriasis

Scalp psoriatic itch is a common complaint and often poses a therapeutic challenge. The pathophysiology of this phenomenon is unclear. The unique anatomy of the scalp contains richly innervated hair follicles, abundant vasculature and perifollicular inflammatory cytokines which may all contribute to this common sensory complaint. The mast cell, in particular, is portrayed as one of the main itch conductors for its ability to trigger neurogenic inflammation, activate the peripheral hypothalamic pituitary adrenal (HPA)-axis, process and integrate itch signaling through its interactions with the scalp hair follicles. Herein we explain and speculate upon potential mechanisms underlying itchy scalp psoriasis, involving interconnections between the neuroimmune, neurovascular, and neuroendocrine systems. Many factors may play roles in itchy scalp psoriasis including the scalp hair structure, immune system, endocrine system, nervous system, and vascular system. These may warrant further exploration as therapeutic targets that go beyond the application of mere anti-inflammatory agents. This article is protected by copyright. All rights reserved.

as reported in: Exp Dermatol. 2019 Apr 25 [Epub ahead of print]