This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
Prurigo nodularis (PN) is a skin disease that causes hard, itchy lumps (nodules) to form on the skin. The itching (pruritus) can be intense, causing people to scratch themselves to the point of bleeding or pain. Scratching can cause more skin lesions to appear. The itching is worsened by heat, sweating, or irritation from clothing. In some cases, people with PN have a history of other diseases including eczema (atopic dermatitis), lymphoma, HIV infection, severe anemia, or kidney disease.
The exact cause of PN is unknown. Although scratching is known to cause more nodules to appear, it is unclear what causes the itching to develop in the first place. Diagnosis of the disease is based on observing signs such as extremely itchy skin with the formation of nodules. In some cases, a skin biopsy is used to confirm the diagnosis. Treatment may include corticosteroid creams, oral medications, cryotherapy, or photochemotherapy.
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