Prurigo simplex
| Prurigo simplex | |
|---|---|
| Specialty | Dermatology  |
Prurigo simplex is a treatment-resistant, idiopathic (occurring spontaneously or from an unknown cause), skin condition characterized by hard, raised bumps on the skin.[1][2] Prurigo simplex includes multiple isolated papules/nodules that cause severe itch.[2] The fundamental concepts and classifications of prurigo have not been established, resulting in confusion regarding the topic.[2] In prurigo simplex, pruritic, or itchy, nodules are arranged in a symmetrical distribution across the body. A nodule is a well-circumscribed, elevated, solid lesion. Nodules can range from a few millimeters to greater than ten millimeters in diameter.[3]
Characterizations[edit]
The most common prurigo simplex symptoms are skin nodules resembling insect bites that are intensely itchy. When those suffering from prurigo simplex scratch the nodules open, they become lesions that continue to itch. The skin thickens and becomes discolored around the nodules. The scalp, arms, legs and torso of the body are the most frequent sites of the bumps and lesions. Itching can become severe and habitual, worsening the condition and possibly causing infections in the open sores.[3] Prurigo is a rare condition that affecting older individuals and is often chronic, lasting years. The lesions rarely resolve completely, returning after the scratch-itch cycle has resolved. The scratch-itch cycle refers to a sensation of itchiness that causes sufferers to scratch, causing further inflammation and rash which exacerbates the itch further. Prurigo is not contagious or hereditary. It is estimated to affect 72 per 100,000 people in the United States and occurs in all genders equally. It can affect quality of life across all age groups but is more common in the elderly, with a median age of 62.[3]
Cause of Prurigo Simplex[edit]
The cause of prurigo is unknown. It occurs in those who have chronic pruritus and is often associated with atopic dermatitis, also known as eczema. Eczema is a skin condition that results in inflamed, irritated, and itchy skin. Prurigo is the result of continuous scratching over a prolonged period of time.[3]
There are systemic and psychiatric diseases that can be associated with severe pruritus. Examples of systemic diseases associated with prurigo include diabetes mellitus, chronic renal failure, cardiovascular disease, hepatitis C, and gluten enteropathy. Prurigo is occasionally seen in individuals with HIV infection, especially if their immune system has been severely compromised. The role of these underlying conditions in prurigo is unclear.
Anxiety, depression, and general emotional stress can also cause prurigo. There are some mechanisms that have been proposed for the cause of prurigo, including an increased number of nerve fibers in the skin in those with prurigo. Nerve growth factor, a neuropeptide, is overexpressed in prurigo lesions, and is involved in the release of substance P, which stimulates inflammation. Prurigo has been considered to be a small-fiber neuropathy, which is a disorder in which the small sensory cutaneous nerves are affected. Studies have found that the nerve fiber density in the skin of those with prurigo is reduced, which could lead to sensory disturbances and itch. Th2 cytokines have been shown to be increased in the skin of those with prurigo. Cytokines are small proteins important for cellular signaling. Th2 cytokines play an important role in the pathophysiology of allergic diseases, including asthma. IL-31, a potent cytokine involved in pruritus, is aberrantly expressed in prurigo nodularis.[3]
Sometimes the nodules become less itchy and eventually disappear, leaving a discolored area or scar. The same nodules can persist for months or even years, though, without healing. Patients may experience a remission but then relapse with new nodules forming. The condition might also become chronic, with no periods of improvement and relief.
Signs and symptoms[edit]
Signs and symptoms of prurigo include intense itching of firm, dome-shaped nodules that are symmetrically distributed on arms and legs, upper back, abdomen, and the sacrum. The nodules can range in size from a few millimeters to several centimeters and can be flesh colored, erythematous, brown or black. An individual can have a few nodules on their body or up to hundreds. The pruritus associated with prurigo is often severe and distressing. Pruritus can be intermittent and sporadic, or continuous. The itching is often exacerbated by heat, sweating, and wearing tight or irritating clothing.[3]
References[edit]
- ^ "Prurigo Nodularis: What It Is, Symptoms, Causes & Treatment". Cleveland Clinic. Retrieved May 12, 2024.
- ^ a b c Satoh, Takahiro; Yokozeki, Hiroo; Murota, Hiroyuki; Tokura, Yoshiki; Kabashima, Kenji; Takamori, Kenji; Shiohara, Tetsuo; Morita, Eishin; Aiba, Setsuya; Aoyama, Yumi; Hashimoto, Takashi; Katayama, Ichiro (July 27, 2021). "2020 guidelines for the diagnosis and treatment of prurigo". The Journal of Dermatology. 48 (9). National Library of Medicine, National Center for Biotechnology: e414–e431. doi:10.1111/1346-8138.16067. ISSN 1346-8138. PMID 34314056.
- ^ a b c d e f Guo, Lily (March 7, 2023). Haag, Alyssa; Miao, Emily; LaFayette, Kelsey; Johnson, Stacy M. (eds.). "Prurigo: What Is It, Causes, Signs, Symptoms and More". Osmosis from Elsevier. Federation of State Medical Boards and the National Board of Medical Examiners. Retrieved May 12, 2024.