The high incidence season and triggering factors of nodular prurigo

About prurigo nodularis

Prurigo nodularis is a chronic, intractable inflammatory skin disease characterized by pruritic nodules. The exact cause of the disease is unknown, but immune and neurological disorders are responsible for the cycle of itching and scratching.

Constant scratching can cause scattered, bruised, nodular, pigmented/purpuric lesions on the skin, with scabs or scales on the surface. Scratching causes desquamation, thickening, and hyperkeratosis of the skin, known as lichen simplex, which may also occur in the form of plaques.

Prurigo nodularis mainly affects the lower limb extensors, but it also often affects the arms and sometimes other parts of the body. Levels of neuropeptides (such as substance P, calcitonin gene-related peptide, and nerve growth factor) are elevated in the skin, as are eosinophils and mast cells.

Patients with prurigo nodularis. It is not clear whether this is the cause or the result of chronic scratching and skin irritation. One study found that patients with prurigo nodularis had hypoplasia of the cutaneous epidermal sensory nerves, even in areas where there was no pruritus problem.

Causes of Prurigo Nodularis

PN is still poorly understood. Although the role of the unimpeded itch-scratch cycle is indisputable, the exact sequence of events leading to the final clinical picture remains controversial. PN is associated with prolonged pruritus and is thought to be a response to repeated scratching in patients with chronic prurigo of various etiologies, including dermatological, systemic, and infectious. Psychiatric disorders were once thought to be a predisposing factor for PN, although later studies have refuted the psychotic cause of PN. Patients report that they have struggled to distinguish themselves from people with mental disorders, such as paranoia and other mental disorders. Data suggest that infectious agents such as hepatitis C, Helicobacter pylori, Strongyloides faecalis, Mycobacterium and HIV have a pathogenic role or association. Some triggers may include: heat, stress, perspiration, humidity, dryness, wool, polyester or rough cloth clothing, personal care products, allergens, etc.

PN lesions. Such neurological changes are typical of PN and are not seen in chronic lichen simplex or neurodermatitis. The density of mast cells and neutrophils also increased in PN, although their degranulation products did not appear to increase. In contrast, although the number of eosinophils remained unchanged, their products, such as major basic proteins and eosinophil-derived neurotoxins, showed higher than normal levels.

PN appears to be the result of cutaneous neurogenic inflammation mediated by various neuropeptides, particularly substance P, calcitonin gene-related peptide (CGRP), and vanillin receptor subtype 1(VR-1). The latter binds to capsaicin, making it a potential topical therapeutic agent. PN patients also exhibit elevated levels of interleukin-31 (IL-31), a T-cell-derived highly pruritic cytokine.

High season

Because of high temperature, humidity and excessive sweating and other factors easy to cause or aggravate the skin itching symptoms. In addition, exposure to allergens, such as pollen, dust, etc., may also cause the onset of prurigo nodularis. Prurigo nodularis (Nodular Prurigo) is usually high in warmer climates, in the spring and summer. For some patients, the dry winter air may also make the skin more sensitive, which can lead to worse conditions.

Reference Source:

[1]https://patient-info.translate.goog/doctor/prurigo-nodularis-pro?_x_tr_sl=en&_x_tr_tl=zh-CN&_x_tr_hl=zh-CN&_x_tr_pto= SC &_x_tr_hist=true

[2]https://patient-info.translate.goog/doctor/prurigo-nodularis-pro?_x_tr_sl=en&_x_tr_tl=zh-CN&_x_tr_hl=zh-CN&_x_tr_pto= SC &_x_tr_hist=true

[3]https://www-ncbi-nlm-nih-gov.translate.goog/books/NBK459204/?_x_tr_sl=en&_x_tr_tl=zh-CN&_x_tr_hl=zh-CN&_x_tr_pto= SC

[4https://en-m-wikipedia-org.translate.goog/wiki/Prurigo_nodularis?_x_tr_sl=en&_x_tr_tl=zh-CN&_x_tr_hl=zh-CN&_x_tr_pto= SC]

Disclaimer: This article is for the purpose of information exchange only, and the views expressed in this article do not represent the position of Zhongyi, nor do they represent support or opposition to the views expressed in this article. This article is not a treatment plan recommend, if you need to get treatment plan guidance, please go to a regular hospital.