Prurigo nodularis (PN) is an intensely itchy skin rash. PN bumps on the skin can range in size from very small to about a half inch in diameter. The number of nodules can vary from 2 to 200.
Common thought is that it occurs as a result of scratching the skin. Itchy skin can be due to a number of reasons, like:
- dry skin
- thyroid dysfunction
- chronic kidney disease
The itching of PN can be debilitating in its severity. It’s thought to have the highest itch intensity of any itchy skin condition.
Scratching makes the itching worse and can cause more bumps to appear and worsen the existing bumps.
PN is challenging to treat. Let’s look at symptoms and ways to manage PN.
PN can start as a small, red itchy bump. It occurs as a result of scratching the skin. The bumps usually start on your arms or legs but can also appear on the rest of your body, wherever you scratch.
The nodules can be intensely itchy. The bumps may be:
- crusty and scaly
- range in color from flesh tones to pink, brown, or black
- warty looking
The skin between bumps can be dry. Some people with PN also experience burning, stinging, and temperature variations in the bumps, according to a 2019 review.
The bumps can develop secondary infections from frequent scratching.
The intense itching can be debilitating, preventing restful sleep and disrupting your daily routine. This in turn can make people with PN feel distressed and depressed.
The bumps may resolve if the person stops scratching them. They may leave scars in some instances.
The aim of PN treatment is to break the itch-scratch cycle by relieving the itching.
Your healthcare provider will need to treat any underlying condition that’s causing your itching and scratching.
The usual PN treatment involves both topical creams and systemic drugs for itch relief.
Because the itching is so severe and each case is different, you may have to try a series of different therapies to find what works best for you.
PN is an understudied disease.
In some individuals, there’s no identifiable cause for the itching. For these people, there’s no single effective treatment.
Currently, the U.S. Food and Drug Administration (FDA) hasn’t approved any therapies to treat PN. However, there are many drugs under investigation that could possibly be used off-label to treat the condition.
Be sure to discuss possible side effects of medications and using medications off-label with your healthcare provider.
Your healthcare provider may suggest some over-the-counter (OTC) or prescription topical remedies to relieve itching and to cool your skin.
Examples can include:
- topical steroid creams such as clobetasol or calcineurin inhibitors such as pimecrolimus. (These may be covered to help them work more effectively.)
- topical coal tar
- topical vitamin D-3 ointment (calcipotriol)
- capsaicin cream
Your healthcare provider may prescribe or suggest OTC antihistamines to help you sleep at night.
Therapies that may help shrink the nodules and relieve itching include:
- Cryotherapy. Cryotherapy is the use of ultra-cold temperatures on the lesion
- Phototherapy. Phototherapy uses ultraviolet light (UV).
- Psoralen used in combination with UV. Psoralen and UVA used together is known as PUVA.
- Pulsed dye laser. Pulsed dye laser is a treatment method used to kill diseased cells.
- Excimer laser treatment. An excimer laser at 308 nanometers has
successfully treatedPN that didn’t respond to other treatments.
Your healthcare provider may also suggest habit reversal therapy to help you stop scratching.
Some trials involving using drugs off-label have shown promise in reducing itching.
- naloxone intravenous and naltrexone oral mu-opioid receptor antagonists, which may have initial side effects
- immunosuppressants, which include cyclosporine and methotrexate
- gabapentinoids, which are used for people who don’t respond to other treatments or who have painful neuropathies
- thalidomide, which has been shown to be effective, but is considered as a last resort because of possible side effects
- nalbuphine and nemolizumab, which are now undergoing testing
- isoquercetin, which is a derivative of plant quercetin
dupilumab, which is an injectable treatment
Everyone’s skin is different, and it may take some time to find a routine that helps your itching.
A combination of remedies may work best. It’s important to try to break the itch-scratch cycle to prevent more nodules and allow the old ones to resolve.
In addition to prescribed medications and OTC creams:
- Use an ice pack to cool itchy areas.
- Take a lukewarm, short bath with colloidal oatmeal.
- Moisturize frequently with Vaseline or a hypoallergenic cream.
- Use fragrance-free soaps and other products for sensitive skin.
The exact cause of PN isn’t fully understood, but the lesions are believed to be a direct result of itchy skin, which can be due to many reasons.
PN has been associated with several conditions, including:
- atopic dermatitis (eczema)
- chronic kidney failure
- chronic hepatitis C
- neurological disorders
- psychiatric disorders
- post-herpetic neuralgia
- lichen planus
- congestive heart failure
- chronic obstructive pulmonary disease (COPD)
- some therapeutic drugs for cancer (pembrolizumab, paclitaxel, and carboplatin)
It’s thought that PN occurs when other conditions cause persistent itching and scratching (an itch-scratch cycle), resulting in the characteristic lesions.
Even when the underlying condition is resolved, PN is said to sometimes persist.
Also, a 2019 study notes that about 13 percent of people with PN have no predisposing illness or factors.
Researchers are looking at the underlying mechanisms involved in PN, which include:
- changes in skin cells
- nerve fibers
- neuropeptides and neuroimmune system changes
As the cause of PN development becomes clearer, researchers expect that better treatments will become possible.
Until the exact causal mechanism of PN is known, it’s difficult to prevent. Not scratching the skin may be the only way.
If you’re predisposed to PN, because of genetics or an underlying disease, monitor your skin carefully. See a healthcare provider for treatment of any long-lasting itchiness. Try to stop any itch-scratch cycle before it starts.
Many remedies can help relieve itching before it becomes difficult to manage.
PN is an intensely itchy skin condition that can be disabling. Its exact cause isn’t fully understood, but it’s known to be associated with several other conditions.
Many treatments are possible, but it may take a while to successfully manage your PN. It’s likely that a combination of topical, drugs, and other therapies will work for you.
The good news is that several new drugs and therapies are under development and undergoing testing. As researchers learn more about the PN mechanism, more targeted effective therapies will be developed.