Prurigo nodularis (PN) is a rare skin condition. It causes a rash and lumps to form on your skin, which may be severely itchy. Treatment involves relieving the itching.
Prurigo nodularis (PN) causes bumps (nodules) on the skin that can range in size from 0.5–2 centimeters in diameter. The number of nodules can vary from 2–200.
The condition may occur as a result of scratching your skin, which may be due to:
- dry skin
- thyroid dysfunction
- chronic kidney disease
That said, the cause is not entirely known.
PN is thought to have the highest itch intensity of any itchy skin condition.
This article looks at the symptoms, causes, and treatment options of PN.
PN can start as a small, red itchy bump that occurs as a result of scratching the skin.
Nodules may appear wherever you scratch. However, they typically appear on your:
- arms
- legs
- back
- stomach area
- buttocks
The nodules can be:
- intensely itchy
- hard
- crusty, scaly, and scabby
- range in color from flesh tones to pink, brown, or black
- warty looking
Some people with PN may also experience burning, stinging, and temperature variations in the bumps.
Nodules can develop secondary infections from a persistent itching and scratching cycle. This itch-scratch cycle may also prevent restful sleep and disrupt your daily routine, which in turn can make you feel distressed and depressed.
In some cases, the nodules leave behind scars after treatment.
The exact cause of PN isn’t fully understood. However, the characteristic lesions may be a direct result of the uncontrollable itch-scratch cycle.
PN has been associated with several conditions that may cause itchiness, including:
- atopic dermatitis (eczema)
- diabetes
- chronic kidney failure
- chronic hepatitis C
- neurological disorders
- psychiatric disorders
- post-herpetic neuralgia
- lymphoma
- lichen planus
- congestive heart failure
- chronic obstructive pulmonary disease (COPD)
- HIV
- some therapeutic drugs for cancer, such as pembrolizumab, paclitaxel, and carboplatin
That said, a 2019 study notes that 13% of people with PN have no predisposing illness or factors.
In some cases, PN may even persist after the underlying condition is resolved.
Researchers are currently looking at the underlying mechanisms involved in PN, which include:
- changes in skin cells
- nerve fibers
- neuropeptides and neuroimmune system changes
Better treatments will become possible as the cause of PN development becomes clearer.
Fast facts
- PN is most common in adults ages 51-65.
- PN affects females more than males.
- A 2018 study involving 909 people with PN found that Black people were
3.4 times more likely to have PN than white people.
The aim of PN treatment is to break the itch-scratch cycle by:
- relieving the itching
- treating any underlying conditions that may cause itching
Since PN is an understudied disease, there’s not always an identifiable cause for the itching.
Currently, the Food and Drug Administration (FDA) has not approved any therapies to treat PN.
However, many drugs under investigation may possibly be used off-label to treat the condition. This means that the medication is approved by the FDA for a certain purpose but is
PN treatment involves both topical creams and systemic drugs for itch relief. You may need to try a series of different therapies to find what works best for you.
Speak with a doctor about any possible side effects you may be experiencing and the use of medications off-label.
Topical drugs
Some over-the-counter (OTC) or prescription topical remedies may help relieve itching and cool your skin.
Examples may include:
- topical steroid creams, such as clobetasol and calcineurin inhibitors
- topical coal tar
- topical vitamin D3 ointment (calcipotriol)
- capsaicin cream
- menthol
Injections
A doctor may suggest corticosteroid (Kenalog) injections for some nodules.
Systemic medications
A doctor may prescribe OTC antihistamines to help you sleep at night.
They may also prescribe medications that are typically used as antidepressants to help you stop scratching. Paroxetine and amitriptyline have had success in helping PN nodules to improve.
Other therapies
Therapies that may help shrink the nodules and relieve itching include:
- cryotherapy
- phototherapy
- psoralen and UVA used together, known as PUVA
- pulsed dye laser, which is a treatment method used to kill diseased cells
- excimer laser treatment, which has
successfully treated PN that did not respond to other treatments
Newer treatments
Some trials involving using drugs off-label have shown promise in reducing itching.
These may include:
- naloxone intravenous and naltrexone oral mu-opioid receptor antagonists
- immunosuppressants, such as cyclosporine and methotrexate
- gabapentinoids, which are used to treat neuropathies
- thalidomide, which is a last resort due to possible side effects
- nalbuphine and nemolizumab, which are now undergoing testing
Isoquercetin and
Home remedies
In addition to prescribed medications and OTC creams, some home remedies may help relieve your itching.
These may include:
- using an ice pack or cold compress to cool itchy areas
- taking a lukewarm, short bath with colloidal oatmeal
- moisturizing frequently with Vaseline or a hypoallergenic cream
- using fragrance-free soaps and other products for sensitive skin
Support
Contact Nodular Prurigo International for more information or to join its private Facebook group or open Facebook group.
Participating in a PN clinical trial is also an option.
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, monitoring your skin carefully is necessary. It’s important to stop an itch-scratch cycle before it starts.
Many remedies can help relieve itching before it becomes difficult to manage.
If itching begins, speak with a healthcare professional as soon as possible for treatment options.
Is nodular prurigo contagious?
PN is not contagious. However, an underlying condition that may be associated with it may be transmissible. For example, HIV may be transmitted from person to person via bodily fluids.
Can prurigo nodularis become cancerous?
A
Is prurigo nodularis an autoimmune disease?
The underlying cause of PN is not known.
However, researchers believe it’s a chronic neural- and immune-mediated disease. This means there are increased sensory nerves that are thickened and an increased inflammatory response at the PN sites.
PN is not classified as an autoimmune disorder, but it’s been associated with other autoimmune diseases, skin disorders, and diseases that lower the immune response.
Is prurigo nodularis a form of psoriasis?
PN may sometimes be mistakenly diagnosed as vulgaris psoriasis. This chronic skin condition leads to similar symptoms as PN, such as dry, inflamed, and itchy skin plaques that could also be scaly.
PN is an intensely itchy skin condition. Its exact cause is not 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 therapies, including topical and drug, will work for you.
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.