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Review
. 2022 Oct 16;23(20):12390.
doi: 10.3390/ijms232012390.

Chronic Nodular Prurigo: An Update on the Pathogenesis and Treatment

Lai-San Wong  1 , Yu-Ta Yen  2   3
Affiliations
Review

Chronic Nodular Prurigo: An Update on the Pathogenesis and Treatment

Lai-San Wong et al. Int J Mol Sci. .

Abstract

Chronic nodular prurigo (CNPG) is a recalcitrant chronic itchy disorder that affects the quality of life. It can be triggered by multiple etiologies, such as atopic dermatitis, diabetes, and chronic renal diseases. The mechanisms of CNPG are complicated and involved the interaction of the cutaneous, immune, and nervous systems. Diverse immune cells, including eosinophils, neutrophils, T cells, macrophages, and mast cells infiltrated the lesional skin of CNPG, which initiated the inflammatory cytokines and pruritogens release. In addition, the interaction between the immune cells and activated peripheral sensory nerve fibers by neurotransmitters caused neuroinflammation in the skin and intractable itch. This itch-scratch vicious cycle of CNPG results in disease exacerbation. CNPG is difficult to treat with traditional therapies. Recently, great advances have been made in the pathophysiology of both inflammation and pruritus transmission in CNPG. In this review, we summarize the updated mechanisms and novel therapies for CNPG.

Keywords: chronic nodular prurigo; pruritus.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
The interplay among the cutaneous, immune, and nervous systems in patients with CNPG. Keratinocyte is a big source of growth factors and inflammatory cytokines, which leads to immune activation. Enhanced infiltration of Th2, Th17/IL-17, Th22/IL-22, eosinophils, and mast cells initiates the inflammatory process and promote keratinocytes hyperproliferation. Simultaneously, neuronal hyperplasia in the dermis further releases neuropeptides, such as substance P, which activate the immune response by interplaying with the immune cells and keratinocytes. The itch-scratch vicious cycle execrates the inflammatory process and scratching causes mechanical damage to peripheral nerve fibers in the epidermis. SP, substance P; NK1R, neurokinin 1 receptor; CST, cortistatin; NGF, nerve growth factor; TrkA, tyrosine kinase receptor A; MRGPRs, Mas-related G-protein-coupled receptors; DRG, dorsal root ganglion.
See this image and copyright information in PMC

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