What To Know about Prurigo Nodularis

Prurigo nodularis (PN) is a chronic (long-term) skin condition that causes intense itching and firm bumps on the outer layer of the skin, known as nodules. As a result of the itching, some people also develop raised plaques on the skin, dry or inflamed patches, and even skin infections. 

PN is often cyclical, meaning that people scratch their skin to relieve the itching, but the scratching often causes more itchy and inflamed skin. However, proper treatment can heal the skin and break this cycle.

Experts don’t know why some people get PN and others don’t, but abnormalities in the nerves and immune system cells located in the top and middle layers of the skin (the epidermis and dermis) seem to be the cause. Historically, it was considered a rare disease. However, estimates of how many people have PN might be low because data has not always been collected properly. The condition may be more common than once thought.

Symptoms

The signs of PN are typically extreme itching and hard bumps on the skin, but these symptoms don’t usually appear all at once. In fact, the nodules form only as a result of scratching the skin in an attempt to relieve the itch.   

Pruritus

In medical terms, pruritus simply means “itching,” and this is the first symptom of PN. There are usually no nodules at this point, only an intensely itchy feeling on the skin. The itching may be constant or come and go, affecting either large areas of your body or only one small area. The affected skin can sometimes also burn or sting.

The most common places people experience pruritus with PN are the arms and legs, upper and lower back, stomach, and buttocks. Environmental factors, like heat and sweat, can trigger or worsen PN, as can psychological factors like stress.

Nodules

After having pruritus for about six weeks, it’s common for hard bumps to develop on the skin as a result of the persistent scratching and rubbing triggered by the itching. These bumps can appear as red, pink, brown, or your skin color. They are typically hard and round, symmetrical, and anywhere from half a centimeter to two centimeters wide. 

Plaques might also develop on the skin alongside nodules. These thick patches may be red, pink, brown, or skin-colored. 

Progressive Symptoms

Over time, especially if PN is left untreated, other symptoms can occur because of prolonged scratching. If nodules or lesions break open, they can bleed or crust over. Skin infections can develop in these open areas if bacteria get inside. Eventually, scars may develop where there was broken skin that later healed.

Prurigo Nodularis Causes

Experts are unsure what causes PN, but they have seen abnormalities in the nerve fibers of the skin in people with PN and a heightened immune system response.

Research shows that people with PN have more nerve fibers in the middle layer of their skin and less in the top layer than people who don’t have PN. Studies also suggest that people with PN have more immune cells in their skin that create inflammatory chemicals called cytokines and other immune cells associated with allergic reactions and inflammation.

Combined, these abnormalities in nerve fibers and immune cells could create heightened sensations of itching and extra inflammation that lead to the development of PN, but why this happens is still unknown. 

Risk Factors

Some people never identify the cause of their PN, but several risk factors make some people more likely to develop the condition than others. These risk factors include:

• Coexisting health conditions: PN occurs more often in people with certain underlying health conditions, such as eczema, contact dermatitis, end-stage kidney disease, hepatitis C, human immunodeficiency virus (HIV) anxiety, and depression.
• Sex: Males and females can develop PN, but the condition tends to be slightly more common and severe in people assigned female at birth.
• Age: Anyone can develop PN, but the disease is most common in people between the ages of 51 and 65.
• Ethnicity: Researchers generally consider Black people to be at a higher risk of PN than other ethnicities, and one study found that Black communities had a three times higher risk of developing PN than white people. However, that study only included participants from one hospital. More research is needed to understand additional risk factors for people from different racial and ethnic backgrounds. 

Diagnosis

Dermatologists typically use a combination of a physical exam and medical history to learn more about your symptoms and overall condition. For example, if you have nodules in parts of the body where PN often develops and the nodules have been intensely itchy, your provider may diagnose you with PN with that information alone.

However, if your provider isn’t sure about your exact diagnosis or wants to rule out skin conditions with similar symptoms, they can perform one of two tests:

• Dermatoscopy: Uses a lighted scope to help your dermatologist get a magnified look at the structure of the top and middle layers of your skin, which can help them diagnose various skin diseases
• Biopsy: Takes a small sample of your skin and examines it under a microscope to look for signs of inflammation, thickened skin, and changes to the nerve fibers in the top and middle skin layers

Prurigo Nodularis Treatment 

PN has no cure, so the goal is to relieve symptoms as much as possible. Your healthcare provider will aim to stop or limit the cycle of itching and scratching so your skin can heal and help you create a plan that reduces future flares (periods where symptoms are active).

There's no one-size-fits-all treatment for PN. Healthcare providers use a variety of medications, therapies, and lifestyle changes to help improve symptoms.

Topical and Injectable medications

Healthcare providers usually start with topical medications to address itching and inflammation, including antihistamines, vitamin D, menthol, capsaicin, and corticosteroid creams. Sometimes, corticosteroids injected into affected skin areas can reduce inflammation more than topical creams can.  

Immunosuppressants

Immunosuppressants are medications that lower your body’s immune system response. These medications can help treat difficult cases of PN. However, immunosuppressants come with certain risks, so your provider may only recommend them if you have severe symptoms.

If you receive a prescription for an immunosuppressant, you'll likely take Neoral (cyclosporine) or Otrexup (methotrexate).

Biologics

Biologics are drugs made in labs with living cells that you can take via injection or infusion.

In 2022, a biologic drug called Dupixent (dupilumab) became the first FDA-approved treatment for PN. Previously, it was only approved for other skin conditions, such as atopic dermatitis. Studies show that this biologic can help reduce the appearance and itchiness of your nodules.

Other Therapies

Your provider may recommend one of the following therapies alongside your biologics, immunosuppressants, or topical and injectable medications. These therapies can also help improve PN symptoms:

• Light therapy to heal skin lesions and reduce itching
• Cryotherapy, which uses freezing temperatures to improve lesions and itching
• Drugs to treat nerve pain, like Horizant (gabapentin)
• Sedatives to help you sleep
• Narcotics such as Narcan (naloxone) to suppress itching

Lifestyle Recommendations

Since scratching causes nodules to form, finding ways to reduce or limit scratching can be helpful. This includes wearing protective items like gloves on your hands and bandages or light fabric coverings on your body. It’s also important to keep your fingernails short and clean. 

Similarly, taking good care of your skin can prevent dryness and reduce itching. Use gentle cleansers and non-irritating lotions or moisturizers on your skin. It can also help to avoid deep scrubbing while you shower or bathe. 

How To Prevent Prurigo Nodularis Episodes

Prurigo nodularis is an inflammatory condition related to the skin’s nerve and immune cells, so there isn’t much you can do to prevent it. If you have PN, you can take steps to reduce flares and symptom severity. Consider these tips:

• Follow your treatment plan as directed
• Find gentle skincare products that work for your symptoms with the help of your dermatologist
• Wear lightweight clothing that covers your skin to help control scratching
• Avoid PN triggers, such as extreme heat, sweat, irritating fabrics, harsh soaps, and fragrances
• Manage stress to help limit the frequency of flares

Related Conditions

There are many conditions related to PN. Some occur before PN, while others are more common in people who have experienced PN for some time. However, experts note that some of these connections may be bidirectional, meaning that they’re both caused by PN and also make PN worse.

Common conditions that occur before PN and increase your risk of developing PN include:

• Dermatitis
• Type 2 diabetes
• Thyroid disease
• Kidney disease
• Liver disease
• Hypertension (high blood pressure)
• Hepatitis C
• Viral, parasitic, or bacterial infections

Living with PN can also increase your risk of other conditions, such as:

• Skin infections
• Anxiety
• Depression
  

Living With Prurigo Nodularis  

PN is a chronic condition—meaning you may have it for years—and there are no established cures or treatment guidelines at the moment. This can often make treatment for PN challenging. Without proper treatment, symptoms can feel intense, lowering your quality of life and disrupting your sleep and overall well-being.

Knowing your triggers for PN and working with healthcare providers to create a maintenance and treatment plan for your symptoms can help you manage or even prevent flares. New medications, like biologic drugs, are becoming more widely used in treating PN because of their effectiveness in improving symptoms. Stay up-to-date on your medications and keep in contact with your provider to learn when new medications are on the market.

Anxiety and depression are common among people with PN. About half of all people with PN experience some mental health concerns. If you notice that your symptoms may be affecting your emotional well-being, ask your loved ones for support. Some people also find it helpful to join a support group or reach out to a mental health professional, such as a therapist, psychologist, or psychiatrist, to learn coping mechanisms.