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Disease Profile

Prurigo nodularis

Prevalence
Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.

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Europe Estimated

Age of onset

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ICD-10

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Inheritance

Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.

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Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.

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X-linked
dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.

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X-linked
recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.

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Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

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Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.

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Not applicable

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Other names (AKA)

Nodular prurigo

Summary

Prurigo nodularis (PN) is a skin disease that causes hard, itchy lumps (nodules) to form on the skin.[1] 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.[2][3] The itching is worsened by heat, sweating, or irritation from clothing.[4] In some cases, people with PN have a history of other diseases including eczema (atopic dermatitis), lymphoma, HIV infection, severe anemia, or kidney disease.[1] 

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.[2][3] 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.[3][4] Treatment may include corticosteroid creams, oral medications, cryotherapy, or photochemotherapy.[1][4][5]

Symptoms

The main symptom of prurigo nodularis (PN) is the formation of hard, very itchy lumps (nodules) on the skin. The nodules can range in size from very small to about half an inch in diameter. The nodules often have a rough, dry top and can range in number from a few to hundreds. Nodules most commonly form on the outer arms, shoulders, and legs. Nodules can also form on the neck and trunk, and they rarely form on the face and palms. They may be lighter or darker in color than the surrounding skin. Scarring may occur after nodules begin to heal.[1][2][3]

The symptoms of PN can begin at any age but are most common in adults between 20-60 years.[2] People who have PN may become very concerned about the appearance of the nodules, and the intensely itchy skin may interfere with sleep or with everyday activities. This can cause people with PN to develop stress and depression.[3]

Cause

The exact cause of prurigo nodularis (PN) is not well-understood. It is thought that nodules are more likely to form when skin has been scratched or irritated in some way. Therefore, the act of a person scratching skin can cause the nodules to form. However, the cause of the skin to originally become intensely itchy is unclear. Many people with PN have a history of eczema (atopic dermatitis), other skin conditions, or allergies.[2] 

When people with PN have a skin biopsy, it can be seen that the nerves in the skin are thickened. It is thought that these thickened nerves may send stronger signals to the brain that the skin is itchy. This can cause a person to scratch the skin, which causes more nodules to form and the nerves to become even more thickened. This cycle, called the itch-scratch cycle, is thought to cause an increase in the number of nodules associated with PN. However, exactly why the skin becomes itchy in the first place is unclear and may vary from person to person.[4]

Diagnosis

Prurigo nodularis may be suspected when a person has signs and symptoms of the disease including intensely itchy skin and the development of nodules on the skin.[4] In some cases, a doctor may wish to perform a skin biopsy to look for signs of the disease such as thickened nerves in the skin.[2] After the diagnosis has been confirmed, other tests such as a blood test and tests of liver and kidney function may be recommended to rule out underlying causes of the disease.[3]

Treatment

Prurigo nodularis (PN) can be challenging to treat because people with the disease may respond to treatments differently. Due to the intensity of the itch, people with PN may try several different treatments without receiving much relief. Some people may try all current treatments available without receiving complete relief. For most people, a combination of several treatments may need to be tried to find out what will work best.

The most commonly used treatments for PN are:[1][3][5][6]

If these treatments are not effective, other procedures may be used. These include cryotherapy, which uses very cold temperatures to try to reduce the size of the nodules, or laser therapy. Some people have used photochemotherapy, which combines the use of a medication that increases the skin’s sensitivity to ultraviolet (UV) rays with special light therapy. In some cases, immunosuppressants have been used to treat PN. If the lesions become infected, antibiotics or antibiotic ointment may be prescribed.[3] 

All treatments are typically used in combination with habit reversal therapy, which aims to reduce the frequency of scratching the skin. This can be helpful in slowing down or stopping the cycle of itching and scratching that is associated with PN. Some people wear gloves while they sleep to reduce scratching.[4] 

You can read further treatment information by visiting the American Osteopathic College of Dermatology (ACOD) information page on prurigo nodularis.[1]

Organizations

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

    Social Networking Websites

      Organizations Providing General Support

        Learn more

        These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

        Where to Start

        • The British Association of Dermatologists has a patient information leaflet about Prurigo nodularis.
        • DermNet NZ is an online resource about skin diseases developed by the New Zealand Dermatological Society Incorporated. DermNet NZ provides information about this condition.

          In-Depth Information

          • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
          • PubMed is a searchable database of medical literature and lists journal articles that discuss Prurigo nodularis. Click on the link to view a sample search on this topic.

            Selected Full-Text Journal Articles

              References

              1. Prurigo Nodularis. American Osteopathic College of Dermatology. https://www.aocd.org/page/PrurigoNodularis. Accessed 4/7/2018.
              2. Oakley A. Nodular prurigo. DermNet NZ. September 2014; https://www.dermnetnz.org/topics/nodular-prurigo/.
              3. Prak AH and De la Rosa KM. Prurigo Nodularis. Medscape Reference. June 5, 2017; https://emedicine.medscape.com/article/1088032-overview.
              4. Watsky K. Prurigo nodularis. UpToDate. March 8, 2018; https://www.uptodate.com/contents/prurigo-nodularis.
              5. Ossorio-García L, Jiménez-Gallo D, Rodríguez-Mateos ME, Arjona-Aguilera C & Linares-Barrios M. Treatment of prurigo nodularis with lenalidomide. Dermatol Ther. March 2017; 30(2):https://www.ncbi.nlm.nih.gov/pubmed/27891738.
              6. Lee HG, Stull C, and Yosipovitch G. Psychiatric disorders and pruritis. Clinics in Dermatology. May-June 2017; 35(3):273-280. https://www.ncbi.nlm.nih.gov/pubmed/28511824.

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